Timeline of Colorado history

This timeline is a chronology of significant events in the history of the U.S. State of Colorado and the historical area now occupied by the state.

 2000s   1900s   1800s   Statehood   Territory   1700s   1600s   1500s   Before 1492 
Main article: History of Colorado
See also: Prehistory of Colorado

2020s
YearDateEvent
2020December 4Time Magazine names 15-year-old Gitanjali Rao of Lone Tree its first "Kid of the Year".
November 3In the 2020 General Election, Colorado voters elect nine U.S. Presidential Electors for Joe Biden, elect John Hickenlooper as new U.S. Senator, re-elect six incumbent U.S. Representatives, and elect Lauren Boebert as new 3rd District U.S. Representative. Democrats retain control of the Colorado General Assembly.
October 30Fishers Peak State Park opens to the public.
October 17The Calwood Fire ignites 3 miles (5 km) northwest of Jamestown. As many as 495 firefighters battle the wildfire as it consumes 10,106 acres (41 km2) of forest and 26 homes.
October 14The East Troublesome Fire ignites north of Hot Sulphur Springs. As many as 794 firefighters battle the wildfire as it consumes 193,812 acres (784 km2) of forest and rangeland to become the second most extensive Colorado wildfire in recorded history. Thousands evacuated, more than 300 homes destroyed, and two residents killed.
September 17The Mullen Fire ignites 7 miles (11 km) west of Centennial, Wyoming. As many as 1,254 firefighters battle the wildfire as it spreads through Carbon County, Wyoming, Albany County, Wyoming, and Jackson County, Colorado and consumes 176,878 acres (716 km2) of forest.
September 6Lightning ignites the Middle Fork Fire 10 miles (16 km) north of Steamboat Springs. As many as 136 firefighters battle the wildfire as it consumes 20,517 acres (83 km2) of forest.
August 14Humans ignite the Williams Fork Fire 9.5 miles (15.3 km) southwest of Fraser. As many as 396 firefighters battle the wildfire as it consumes 14,833 acres (60 km2) of forest.
August 13The Cameron Peak Fire ignites 15 miles (24 km) southwest of Red Feather Lakes. As many as 1,903 firefighters battle the wildfire as it consumes 208,913 acres (845 km2) of forest to become the most extensive Colorado wildfire in recorded history, surpassing the ongoing Pine Gulch Fire. Thousands evacuated, 209 homes destroyed.
August 10Humans ignite the Grizzly Creek Fire in Glenwood Canyon of the Colorado River. The wildfire closes Interstate 70, the Union Pacific Railroad, and the Amtrak California Zephyr for two weeks. As many as 889 firefighters battle the wildfire as it consumes 32,631 acres (132 km2) of forest.
July 31Lightning ignites the Pine Gulch Fire 18 miles (29 km) north of Grand Junction. As many as 466 firefighters battle the wildfire as it consumes 139,007 acres (563 km2) of forest and rangeland to become the most extensive Colorado wildfire in recorded history, only to be surpassed by the Cameron Peak Fire seven weeks later.
June 16Colorado Governor Jared Polis issues a statewide COVID-19 mask order.
April 26Colorado Governor Jared Polis rescinds his statewide Stay-at-Home order while requiring continued COVID-19 precautions.
April 1The 2020 United States Census enumerates the population of the State of Colorado, estimated to be about 5,827,000. Colorado may gain an 8th Congressional seat.
March 28U.S. President Donald Trump declares that a major disaster exists in the State of Colorado as a result of the COVID-19 pandemic.
March 25Colorado Governor Jared Polis issues the first Colorado Stay-at-Home order effective at 6:00 a.m. the following morning.
March 13A woman in El Paso County becomes the first person in Colorado to die from the COVID-19 virus.
March 10Colorado Governor Jared Polis declares a Colorado state of emergency in response to the COVID-19 pandemic.
March 5A visitor to Summit County becomes the first person in Colorado to test positive for the COVID-19 virus.
February 11United States Senator Michael Bennet of Denver ends his campaign for President of the United States.

2010s
YearDateEvent
2019September 8Lightning ignites the Decker Fire in the Sangre de Cristo Wilderness. Up to 720 firefighters will battle the wildfire which will consume 8,959 acres (36 km2) of forest.
August 15Former governor John Hickenlooper ends his campaign for President of the United States.
July 20An ambient air temperature of 115 °F (46.1 °C) at John Martin Dam sets the official Colorado all-time high temperature record.
May 7Two armed students attack STEM School Highlands Ranch killing one student and wounding eight others.
May 2United States Senator Michael Bennet of Denver announces his candidacy for President of the United States.
April 26The Regional Transportation District begins operation of its commuter rail G line between Denver Union Station and Wheat Ridge.
March 17Mikaela Shiffrin of Eagle-Vail wins her third consecutive International Ski Federation Women's Overall World Cup.
March 13Winter Storm Ulmer undergoes explosive cyclogenesis as it rips across the Southern Rocky Mountains of Colorado. The bomb cyclone blizzard with hurricane-force winds sets all-time record low barometric pressure readings across the state.
March 4Former governor John Hickenlooper of Denver announces his candidacy for President of the United States.
January 8Jared Polis of Boulder assumes office as the forty-third Governor of the State of Colorado.
2018November 6In the 2018 General Election, Democrats win all five Colorado statewide offices and control of the Colorado General Assembly. Republicans retain three of the state's seven Congressional seats.
June 28Lightning ignites the Weston Pass Fire 9 miles (14 km) southwest of Fairplay. The wildfire will burn 13,023 acres (53 km2) of forest.
June 7An illegal campfire ignites the Spring Creek Fire 9 miles (14 km) northeast of Fort Garland. The wildfire will burn 251 homes and 108,045 acres (437 km2) of forest.
June 1An antique steam locomotive ignites the 416 Fire 10 miles (16 km) north of Durango. The wildfire will burn 54,129 acres (219 km2) of forest over a period of six months.
April 17The Mile Marker 117 Fire ignites 17 miles (27 km) north of Pueblo. The wildfire will burn 42,795 acres (173 km2) of grassland.
The Badger Hole Fire ignites near Walsh. The wildfire will burn 50,815 acres (206 km2) of grassland with 33,609 acres (136 km2) in Colorado and 17,206 acres (70 km2) in Kansas.
March 18Mikaela Shiffrin of Eagle-Vail wins her second consecutive International Ski Federation Women's Overall World Cup.
March 17The attack submarine USS Colorado (SSN-788) is commissioned at the Naval Submarine Base New London.
March 2The Colorado House of Representatives expels State Representative Steve Lebsock for inappropriate behavior.
February 15Mikaela Shiffrin of Eagle-Vail wins the Women's Alpine Skiing Giant Slalom Gold Medal at the XXIII Olympic Winter Games in Pyeongchang, Korea.
February 11Red Gerard of Silverthorne wins the Men's Snowboarding Slopestyle Gold Medal at the XXIII Olympic Games in Pyeongchang, Korea.
2017November 19Martin Truex Jr. of Denver wins the 2017 NASCAR Cup.
October 8Eleven-year-old Gitanjali Rao of Lone Tree wins the 2017 Discovery Education 3M Young Scientist Challenge for her invention of a device that can detect lead in water faster than existing techniques.
April 10United States Circuit Court Judge Neil Gorsuch of Boulder is sworn in as the 101st Associate Justice of the Supreme Court of the United States.
March 18Mikaela Shiffrin of Eagle-Vail wins the International Ski Federation Women's Overall World Cup.
2016August 20The Denver Outlaws defeat the Ohio Machine 19 to 18 to win their second Major League Lacrosse Steinfeld Cup.
June 19A child starts the Beaver Creek Fire near Walden. The wildfire will burn one home, 16 outbuildings, and 38,380 acres (155 km2) of forest.
March 22The Regional Transportation District begins operation of its commuter rail A line between Denver Union Station and Denver International Airport.
February 7The Denver Broncos defeat the Carolina Panthers 24 to 10 to win Super Bowl 50. Von Miller is named the Super Bowl Most Valuable Player. Quarterback Peyton Manning wins his second Super Bowl and his 200th NFL game.
January 24The Denver Broncos defeat the New England Patriots 20 to 18 to win the American Football Conference Championship for the eighth time.
2015February 19U.S. President Barack Obama issues a proclamation creating Browns Canyon National Monument on 21,586 acres (87 km2) of Bureau of Land Management land.[1][2]
January 2Cory Gardner of Yuma assumes office as the junior United States Senator from Colorado.
2014October 6Immediately following a declination by the United States Supreme Court, Colorado Attorney General John Suthers declares that same-sex marriage will be legal in Colorado as soon as legal stays can be lifted.
August 23The Denver Outlaws defeat the Rochester Rattlers 12 to 11 to win their first Major League Lacrosse Steinfeld Cup.
July 26The Regional Transportation District reopens Denver Union Station marking the conclusion of a $56 million redevelopment into a regional multimodal transit hub.
May 25A 40,000,000 cu yd (31,000,000 m3) landslide breaks loose on Grand Mesa near Collbran, hits speeds of more than 50 mph (80 km/h), and kills three men.
February 21Mikaela Shiffrin of Vail wins the women's alpine skiing slalom gold medal at the XXII Olympic Winter Games in Sochi, Russia.
February 2The Denver Broncos lose Super Bowl XLVIII to the Seattle Seahawks 43 to 8 to become the first team to lose the Super Bowl five times.
January 19The Denver Broncos defeat the New England Patriots 26 to 16 to win the American Football Conference Championship for the seventh time.
January 1Colorado becomes the first U.S. state to legalize cannabis for recreational use.
2013September 12Floods along the Front Range Urban Corridor kill 9 people. More than 22,000 residents are evacuated including 1,000 by military helicopters. More than 30,000 homes are damaged and 1800 are destroyed. Total damages will exceed $2.9 billion.
September 10A recall election removes State Senate President John Morse and State Senator Angela Giron from office.
July 18The Royal Gorge fire destroys buildings and the aerial tram at the Royal Gorge Bridge and Park after starting on June 11.
June 13The Black Forest fire north of Colorado Springs surpasses the Waldo Canyon fire as the most destructive in state history. A total of 486 homes will be destroyed by June 20.
June 11Lightning ignites the Big Meadows fire in Rocky Mountain National Park.
June 5Lightning ignites the first of the West Fork Complex fires near Wolf Creek Pass. The wildfires will burn 109,049 acres (441 km2) of forest.
May 1An Act of the Colorado General Assembly makes civil unions legal in Colorado for both conventional and same-sex couples, although same-sex marriage remains illegal for 17 months.
March 20Governor John Hickenlooper signs three bills intended to curb firearm violence.
March 19Tom Clements, Executive Director of the Colorado Department of Corrections, is assassinated at his home in Monument.
2012December 10David J. Wineland of the National Institute of Standards and Technology and the University of Colorado Boulder and Serge Haroche receive the 2012 Nobel Prize in Physics.
November 6Voters approve Colorado Amendment 64 legalizing possession of small quantities of cannabis.
September 21U.S. President Barack Obama issues a proclamation creating Chimney Rock National Monument on 4,726 acres (19 km2) of the San Juan National Forest.[1]
July 30Missy Franklin of Centennial wins the first of four gold medals in swimming at the Games of the XXX Olympiad in London.
July 20A gunman opens fire in a cinema in an Aurora, Colorado screening The Dark Knight Rises, killing 12 people and wounding 70 others.
June 25Sparks ignite the Last Chance Fire on the prairie near Last Chance. This wildfire will burn four homes, seven outbuildings, and 44,000 acres (178 km2) of grassland in a few hours.
June 23The Waldo Canyon Fire ignites west of Colorado Springs. The wildfire will destroy 347 homes.
June 9A lightning strike ignites the High Park Fire west of Fort Collins. The wildfire will kill one person and destroy 248 homes and 87,250 acres (353 km2) of forest.
April 28The History Colorado Center opens in Denver.
March 16Lindsey Vonn of Vail wins her fourth International Ski Federation Women's Overall World Cup.
2011November 18The Clyfford Still Museum opens in Denver.
October 22Missy Franklin of Centennial sets her first swimming world record at the Fédération Internationale de Natation (FINA) Swimming World Cup in Berlin.
September 23Occupy Denver begins a protest of the growing disparity of wealth and political power in the United States.
July 18Michael Hancock assumes office as the Mayor of the City and County of Denver.
April 1CenturyLink, Inc. completes its $24 billion acquisition of the larger Qwest Communications International, Inc. of Denver.
January 12Deputy Major Bill Vidal assumes office as the Mayor of the City and County of Denver to replace John Hickenlooper.
January 11John Hickenlooper assumes office as the forty-second Governor of the State of Colorado.
2010November 21The Colorado Rapids defeat FC Dallas 2 to 1 to win their first Major League Soccer Cup.
November 6The City of Castle Pines North votes to change its name to the City of Castle Pines. The City of Castle Pines is the youngest of the 271 active municipalities of the State of Colorado.[3]
October 14Workers uncover a trove of Pleistocene fossils at the Snowmastodon site while excavating a reservoir near Snowmass Village.
September 6The Fourmile Canyon fire begins west of Boulder. The wildfire will destroy 169 homes.
April 1The 2010 United States Census enumerates the population of the State of Colorado, later determined to be 5,029,196, an increase of 16.92% since the 2000 United States Census. Colorado becomes the 22nd most populous of the 50 U.S. states.
March 14Lindsey Vonn of Vail wins her third consecutive International Ski Federation Women's Overall World Cup.
February 17Lindsey Vonn of Vail wins the women's alpine skiing downhill gold medal at the XXI Olympic Winter Games at Whistler Blackcomb.

2000s
YearDateEvent
2009October 15The balloon boy hoax discombobulates emergency services in northeastern Colorado.
March 15Lindsey Vonn of Vail wins her second consecutive International Ski Federation Women's Overall World Cup.
February 27The Rocky Mountain News, the region's oldest and second highest circulation newspaper, publishes its last edition just 55 days before of its sesquicentennial (c.f. April 23, 1859.) The Denver Post survives as the city's only major newspaper.
January 21Michael Bennet of Denver assumes office as the junior United States Senator from Colorado.
January 3Mark Udall of Eldorado Springs assumes office as the junior United States Senator from Colorado.
2008August 28Barack Obama accepts the nomination of the Democratic National Convention in Denver for President of the United States.
August 13Jack Weil, founder and CEO of Rockmount Ranch Wear, dies at his home in Denver at age 107.
August 4The extension of Interstate Highway I-270 from I-76 to the intersection of I-25 and US 36 opens to traffic, lengthening I-270 to 7.107 miles (11.438 km).
June 10Lightning ignites the Bridger Fire on the U.S. Army Piñon Canyon Maneuver Site. The fire will burn 46,612 acres (189 km2) of forest and grassland.
March 15Lindsey Vonn of Vail wins the International Ski Federation 2008 Women's Overall World Cup.
February 16The Bradford Washburn American Mountaineering Museum opens in Golden.
February 11The Luis A. Jiménez, Jr. sculpture Blue Mustang is unveiled at Denver International Airport. The sculpture will attain local notoriety as Blucifer for killing its creator on June 13, 2006.
January 2EchoStar Communications Corporation of Englewood splits into EchoStar Corporation and Dish Network Corporation.
2007November 6The City of Castle Pines North incorporates.[3]
October 28The Boston Red Sox defeat the Colorado Rockies in four games to win the 2007 World Series.
October 15The Colorado Rockies defeat the Arizona Diamondbacks in four games to win their first National League Pennant.
AugustThe Anschutz Medical Campus of the University of Colorado Denver opens.
July 12The United States Fish and Wildlife Service establishes the Rocky Flats National Wildlife Refuge.
April 27The United States National Park Service establishes the Sand Creek Massacre National Historic Site, commemorating the Sand Creek Massacre on November 29, 1864.[2]
April 7The Colorado Rapids defeat D.C. United 2 to 1 in their first game played in the new Dick's Sporting Goods Park.
January 9Bill Ritter assumes office as the forty-first Governor of the State of Colorado.
2006November 17The T-REX Project in southeast metropolitan Denver is completed 22 months ahead of schedule.
November 7Voters approve an amendment to the Constitution of the State of Colorado banning same-sex marriage.
October 7The Denver Art Museum opens its Daniel Libeskind designed Frederic C. Hamilton Building.
July 28The North American Aerospace Defense Command (NORAD) moves the operations of the Cheyenne Mountain Complex to Peterson Air Force Base.
June 13Sculptor Luis A. Jiménez, Jr. is killed in his Hondo, New Mexico studio assembling his Blue Mustang sculpture intended for Denver International Airport.
May 20The Denver Outlaws defeat the Chicago Machine 24 to 14 in their first Major League Lacrosse game.
May 13The Colorado Mammoth defeat the Buffalo Bandits 16 to 9 to win their first National Lacrosse League Champion's Cup.
2005December 10Professor John L. Hall of the University of Colorado Boulder, Theodor W. Hänsch, and Roy J. Glauber receive the 2005 Nobel Prize in Physics.
June 13The Cussler Museum opens in Arvada.
JuneThe Lawrence Argent sculpture I See What You Mean, locally known as the Blue Bear, is erected outside the Colorado Convention Center in Denver. The sculpture will become a beloved symbol of Denver.
January 1An Act of Congress changes the name of the Colorado Canyons National Conservation Area to the McInnis Canyons National Conservation Area.
2004November 2U.S. President George W. Bush defeats Colorado native John Kerry in the 2004 U.S. presidential election.
September 24U.S. President George W. Bush signs An Act to provide for the establishment of the Great Sand Dunes National Park and Preserve and the Baca National Wildlife Refuge in the State of Colorado, and for other purposes, creating Great Sand Dunes National Park and Preserve from Great Sand Dunes National Monument and creating the Baca National Wildlife Refuge.[2]
June 4An irate citizen of Granby goes on a rampage with a self-built armored bulldozer destoying $7,000,000 worth of property before killing himself.
2003November 24The Northwest Parkway toll road from Broomfield to the intersection of I-25 and E-470 opens to traffic.
July 18John Hickenlooper assumes office as the Mayor of the City and County of Denver.
April 8The United States Fish and Wildlife Service establishes the Baca National Wildlife Refuge.
January 3The last segment of the E-470 toll road opens to traffic.
2002December 4U.S. President George W. Bush signs An Act to amend the National Trails System Act to designate the Old Spanish Trail as a National Historic Trail, creating the Old Spanish National Historic Trail.
June 9The Missionary Ridge Fire starts burning in the mountains north of Durango. The wildfire will kill one firefighter and burn 46 homes and 71,739 acres (290 km2) of forest.
June 8A U.S. Forest Service technician ignites the Hayman Fire in the mountains of central Colorado. The wildfire will burn 133 homes, 467 outbuildings, and 137,760 acres (557 km2) of forest, the most in Colorado recorded history.
2001December 10Professor Eric Allin Cornell of the University of Colorado Boulder, Carl Wieman, and Wolfgang Ketterle receive the 2001 Nobel Prize in Physics.
November 15The Colorado General Assembly creates the City and County of Broomfield from portions of Boulder, Adams, Jefferson, and Weld counties.[4]
JuneConstruction on the T-REX Project in southeast metropolitan Denver begins.
June 9The Colorado Avalanche defeat the New Jersey Devils in seven games to win their second Stanley Cup.
January 1Denver celebrates the arrival of the Third Millennium with fireworks above the 16th Street Mall after canceling last year's celebrations for safety concerns.[5]
2000October 24U.S. President Bill Clinton signs an act of Congress creating the Colorado Canyons National Conservation Area and the Black Ridge Canyons Wilderness.
October 1The State of Colorado transfers Buckley Air National Guard Base back to the United States Air Force as Buckley Air Force Base.
August 21Xcel Energy Inc. is formed by the merger of New Century Energies, Inc. of Denver into the smaller Northern States Power Company.
June 30US West, Inc. of Denver merges into the smaller Qwest Communications International, Inc., also of Denver.
June 9U.S. President Bill Clinton issues a proclamation creating Canyons of the Ancients National Monument.[1]
May 9The Denver Museum of Natural History changes its name to the Denver Museum of Nature and Science.
April 7The American Association of State Highway and Transportation Officials (AASHTO) approves the extension of the Interstate Highway I-270 designation from I-76 northwest to the intersection of I-25 and US 36.
April 1The 2000 United States Census enumerates the population of the State of Colorado, later determined to be 4,301,262, an increase of 30.56% since the 1990 United States Census. Colorado becomes the 24th most populous of the 50 U.S. states and gains a 7th Congressional District.

1990s
YearDateEvent
1999October 21U.S. President Bill Clinton signs An Act to redesignate the Black Canyon of the Gunnison National Monument as a national park and establish the Gunnison Gorge National Conservation Area, and for other purposes, creating Black Canyon of the Gunnison National Park and the Gunnison Gorge National Conservation Area.[1][2]
April 20The Columbine High School massacre begins when two high school students open fire on their campus in Jefferson County killing 12 students and a teacher and wounding 24 others before killing themselves.
January 31The Denver Broncos defeat the Atlanta Falcons 34 to 19 in Super Bowl XXXIII. Quarterback John Elway wins his second consecutive Super Bowl and his 148th NFL game, and is named the Super Bowl Most Valuable Player.
January 17The Denver Broncos defeat the New York Jets 23 to 10 to become the first team to win the American Football Conference Championship six times.
January 12Bill Owens assumes office as the 40th Governor of the State of Colorado.
1998June 5The United States Air Force renames Falcon Air Force Base as Schriever Air Force Base.
January 25The Wild Card Denver Broncos defeat the Green Bay Packers 31 to 24 in Super Bowl XXXII. Terrell Davis is named the Super Bowl Most Valuable Player.
January 11The Wild Card Denver Broncos defeat the Pittsburgh Steelers 24 to 21 to win the American Football Conference Championship for the fifth time.
1997August 13The animated television series South Park debuts. The series set in the fictional town of South Park, Colorado in the real mountain basin of South Park, will become the longest running TV series with a Colorado setting.
August 1New Century Energies, Inc. of Denver is formed by the merger of Southwestern Public Service Company with the larger Public Service Company of Colorado.
June 20The Group of Eight's 23rd annual meeting convenes in Denver.
January 3Diana DeGette of Denver succeeds Congresswoman Pat Schroeder in the United States House of Representatives.
1996December 26The body of JonBenét Ramsey is found in the basement of her home in Boulder.
September 11The Southern Pacific Transportation Company merges with the UP Holding Company, Inc. to form the Union Pacific Corporation. The Southern Pacific Railroad becomes part of the Union Pacific Railroad.
July 22Amy Van Dyken of Englewood wins the first of her six Olympic gold medals in swimming at the Games of the XXVI Olympiad in Atlanta.
June 11The Colorado Avalanche defeat the Florida Panthers in four games to win their first Stanley Cup, becoming the first major league sports team to bring a championship trophy to Colorado.
May 20The United States Supreme Court rules in Romer v. Evans that Colorado Amendment 2 approved in 1992 violates the United States Constitution.
April 13The Colorado Rapids lose to Sporting Kansas City 3 to 0 in their first Major League Soccer game.
1995December 28EchoStar Communications Corporation of Englewood successfully launches its first satellite, EchoStar I.
October 6The Colorado Avalanche defeat the Detroit Red Wings 3 to 2 in their first game since relocation.
June 11Denver International Airport opens replacing Stapleton International Airport.
April 26The Colorado Rockies defeat the New York Mets 11 to 9 in the first game played in the new Coors Field.
March 25The Michael Graves designed addition to the central Denver Public Library opens.
1994December 15The Town of Foxfield incorporates.[3]
December 10Rashaan Salaam of the University of Colorado Buffaloes football team wins the 1994 Heisman Trophy.
October 7The Regional Transportation District begins light rail service in Denver.
July 6A blowup of the South Canyon Fire kills 14 wildlands firefighters on Storm King Mountain, near Glenwood Springs.
1993December 15Colorado district judge Jeffrey Bayless rules that Colorado Amendment 2 violates the United States Constitution.
September 15The interchange of I-76 with I-25 is opened, completing the extended 188.10-mile (302.72 km) length of Interstate Highway I-76 in Colorado. This project completes the original design of the Interstate Highway System in Colorado, although improvements and enhancements will continue.
August 10Pope John Paul II arrives in Denver to celebrate World Youth Day. This is the first visit to Colorado by a pope.
AprilConstruction begins to directly connect the intersection of I-270 and I-76 with the intersection of I-25 and US 36.
April 9The Colorado Rockies defeat the Montreal Expos 14 to 4 in their very first home game.
April 5The Colorado Rockies lose their very first game to the New York Mets 3 to 0.
July 13Steve Ells opens the first Chipotle Mexican Grill at 1644 East Evans Avenue in Denver.
1992November 3Voters approve Colorado Amendment 2 to the state constitution which prohibits "special rights" based upon sexual orientation. Amendment 2 never takes effect due to legal challenges.
Voters approve Colorado Amendment 1 to the state constitution, also known as the Colorado Taxpayer Bill of Rights (TABOR).
October 14Governor Roy Romer dedicates the segment of I-70 through Glenwood Canyon, completing the extended 449.589-mile (723.543 km) length of Interstate Highway I-70 through Colorado.
October 9U.S. President George H.W. Bush signs an act of Congress creating the Rocky Mountain Arsenal National Wildlife Refuge.
August 3U.S. President George H.W. Bush signs an An Act to amend the National Trails System Act to designate the California National Historic Trail and Pony Express National Historic Trail as components of the National Trails System.
May 26U.S. President George H.W. Bush signs an act of Congress creating the Two Ponds National Wildlife Refuge.
1991October 15The Warren Zevon album Mr. Bad Example is released with the song "Things to Do in Denver When You're Dead".
September 16U.S. President George H.W. Bush announces the promotion of the Solar Energy Research Institute to the National Renewable Energy Laboratory (NREL), a national laboratory of the United States Department of Energy.
July 1Wellington Webb assumes office as the first African-American Mayor of the City and County of Denver.
JuneThe first segment of the E-470 toll road opens to traffic.
January 1The University of Colorado Buffaloes football team defeat the University of Notre Dame Fighting Irish 10 to 9 to win the Orange Bowl and the Associated Press National Championship Trophy.
1990November 26The United States Army transfers the Piñon Canyon Maneuver Site to Comanche National Grassland.[6]
November 24The U.S. Environmental Protection Agency vetoes the Two Forks Dam Project proposed by the Denver Board of Water Commissioners.
November 7The Colorado Fuel & Iron company in Pueblo files for Chapter 11 bankruptcy protection.
June 23The Colorado Convention Center opens in Denver.
April 1The 1990 United States Census enumerates the population of the State of Colorado, later determined to be 3,294,394, an increase of 13.99% since the 1980 United States Census. Colorado becomes the 26th most populous of the 50 U.S. states.
January 28The San Francisco 49ers defeat the Denver Broncos 55 to 10 in Super Bowl XXIV.
January 14The Denver Broncos defeat the Cleveland Browns 37 to 21 to win the American Football Conference Championship for the fourth time.

1980s
YearDateEvent
1989December 10Professor Thomas Cech of the University of Colorado Boulder and Sidney Altman receive the 1989 Nobel Prize in Chemistry.
November 22The City and County of Denver holds a ground-breaking ceremony for a new airport to replace the aging Stapleton International Airport.
June 6The Federal Bureau of Investigation and the Environmental Protection Agency raid the Department of Energy Rocky Flats Plant near Arvada.
1988November 8Voters in Adams, Arapahoe, Boulder, Denver, Douglas, and Jefferson counties approved the creation of the Scientific and Cultural Facilities District.
October 13The Denver and Rio Grande Western Railroad becomes part of the Southern Pacific Railroad when Rio Grande Industries, Inc. acquires the Southern Pacific Transportation Company.
June 18The United States Air Force renames Falcon Air Force Station as Falcon Air Force Base.
January 31The Washington Redskins defeat the Denver Broncos 42 to 10 in Super Bowl XXII.
January 17The Denver Broncos defeat the Cleveland Browns 38 to 33 to win the American Football Conference Championship for the third time.
1987May 8U.S. President Ronald Reagan signs An Act to amend the National Trails System Act to designate the Santa Fe Trail as a National Historic Trail, creating the Santa Fe National Historic Trail.
U.S. Senator Gary Hart announces the end of his presidential campaign which began the previous month.
April 5The National Mining Hall of Fame and Museum opens in Leadville.
January 13Roy Romer assumes office as the thirty-ninth Governor of the State of Colorado.
January 25The New York Giants defeat the Denver Broncos 39 to 20 in Super Bowl XXI.
January 11The Denver Broncos defeat the Cleveland Browns 23 to 20 in overtime to win the American Football Conference Championship for the second time. The Drive becomes a part of American football lore.
1985September 26The United States Air Force opens the Consolidated Space Operations Center at Falcon Air Force Station near Colorado Springs.
February 1An ambient air temperature of −61 °F (−51.7 °C) at Maybell sets the official Colorado all-time low temperature record.
1984NovemberThe Anschutz Corporation acquires Rio Grande Industries for $500 million. The new Rio Grande Holdings, Inc. includes the Denver and Rio Grande Western Railroad.
August 1A truck carrying six torpedoes for the United States Navy overturns and dumps its potentially explosive load into the intersection of I-25 and I-70 in Denver, the busiest intersection in Colorado known locally as the Mousetrap.
June 18Alan Berg is murdered at his home in Denver by members of The Order.
February 16Scott Hamilton wins the Olympic gold medal in Men's Figure Skating at the XIV Olympic Winter Games in Sarajevo.
January 1US West, Inc. of Denver is formed by the Bell System divestiture as a holding company with Mountain States Telephone and Telegraph (dba Mountain Bell), Northwestern Bell Telephone Company (dba Northwestern Bell), and Pacific Northwest Bell Telephone Company (dba Pacific Northwest Bell).
1983July 1Federico Peña assumes office as the first Hispanic Mayor of the City and County of Denver.
June 5The Irish band U2 performs at the Red Rocks Amphitheatre in a concert recorded as U2 Live at Red Rocks: Under a Blood Red Sky.
May 17The United States Air Force begins construction of Falcon Air Force Station near Colorado Springs.
1982December 28Congressman-elect and former astronaut Jack Swigert of Littleton dies in Washington, D.C. at age 51.
October 4The 16th Street Mall in Denver opens.
April 3The Colorado Rockies defeat the Calgary Flames 3 to 1 in their final National Hockey League game. In their six NHL seasons, the Rockies compiled a record of 113 wins, 283 losses, and 86 ties.
1981October 1The annexation of the Broadmoor, Skyway, Ivywild, Cheyenne Canon, and Stratton Meadows neighborhoods by the City of Colorado Springs is upheld by the Colorado Supreme Court after a District Court voided the annexation.
January 12The television series Dynasty debuts. The series will become the longest running non-animated TV series set in Colorado (8 seasons, c.f. Dr. Quinn, Medicine Woman 6 sessions, Mork & Mindy 4 sessions).
1980December 9Charlie Ergen, Jim DeFranco, and Cantey McAdams form EchoSphere in Littleton.
April 1The 1980 United States Census enumerates the population of the State of Colorado, later determined to be 2,889,964, an increase of 30.93% since the 1970 United States Census. Colorado becomes the 28th most populous of the 50 U.S. states and gains a 6th Congressional District.

1970s
YearDateEvent
1979December 25Pope John Paul II grants the Cathedral of the Immaculate Conception in Denver the title Basilica minor.
December 21Governor Dick Lamm dedicates the Edwin C. Johnson Bore of the Eisenhower–Johnson Memorial Tunnel completing the section of Interstate Highway 70 under the Continental Divide.
November 1Congressman Ken Kramer leaks the location selected for the Consolidated Space Operations Center east of Colorado Springs.
1978November 10U.S. President Jimmy Carter signs the National Parks and Recreation Act of 1978 authorizing the Continental Divide National Scenic Trail, the Mormon Pioneer National Historic Trail, and the Oregon National Historic Trail.
October 11U.S. President Jimmy Carter signs An Act to create the Indian Peaks Wilderness Area and the Arapaho National Recreation Area, to authorize the Secretary of the Interior to study the feasibility of revising the boundaries of the Rocky Mountain National Park, and to add certain lands to the Oregon Islands Wilderness, creating the Indian Peaks Wilderness Area and the Arapaho National Recreation Area.
October 9The United Nations Educational, Scientific and Cultural Organization (UNESCO) designates designates Mesa Verde National Park as one of the first 12 World Heritage Sites.
September 14The comedy television series Mork & Mindy, set in Boulder, debuts.
August The Town of Avon incorporates.[3]
August 1The United States Olympic Committee moves into its new headquarters at the United States Olympic Training Center in Colorado Springs.
U.S. Highway 36 is extended westward along State Highway 66 from Estes Park to Deer Ridge Junction in Rocky Mountain National Park.
February 26Boettcher Concert Hall of the Denver Center for the Performing Arts opens in the Denver Performing Arts Complex.
January 15The Dallas Cowboys defeat the Denver Broncos 20 to 17 in Super Bowl XII.
January 1The Denver Broncos defeat the Oakland Raiders 20 to 17 to win their first American Football Conference Championship.
1977September 30Proposed Colorado Interstate Highway I-470 is withdrawn from the Interstate Highway System.
July 28Governor Dick Lamm requests that the proposed 26.3-mile (42.3 km) Colorado Interstate Highway I-470 be withdrawn from the Interstate Highway System.
July 5The United States Department of Energy opens the Solar Energy Research Institute (SERI) in Golden.
JuneThe United States Olympic Training Center at the former Ent Air Force Base in Colorado Springs opens to athletes.
1976October 22The Denver Nuggets defeat the Indiana Pacers 123 to 110 in their first game as a National Basketball Association franchise.
October 5The Colorado Rockies defeat the Toronto Maple Leafs 4 to 2 in their first National Hockey League game since relocation.
October 1Ent Air Force Base closes in Colorado Springs.
August 1A somber State of Colorado observes its centennial as it assesses the damage from the Big Thompson Flood the previous evening.
July 31A flash flood in Big Thompson Canyon kills 143 people just hours before the Colorado State Centennial.
July 4The State of Colorado celebrates the Bicentennial of the United States of America.
May 21The final segment of I-225 is opened in Denver, completing the entire 11.959-mile (19.246 km) length of Interstate Highway I-225.
May 13The New York Nets defeat the Denver Nuggets 112 to 106 in the last American Basketball Association game ever played. The Denver Rockets/Nuggets finish their nine seasons in the ABA with a record of 474 wins and 432 losses.
March 1The United States Air Force renames Peterson Field in Colorado Springs as Peterson Air Force Base.
1975August 18Construction of the second bore of the Eisenhower Tunnel begins.
April 1Ent Air Force Base is downgraded to the Ent Annex of the Cheyenne Mountain Air Force Station.
January 14Dick Lamm assumes office as the thirty-eighth Governor of the State of Colorado.
1974December 21The first Telluride Film Festival begins.
October 16The Denver Nuggets lose to the Kentucky Colonels 117 to 99 in their first game since the team name was changed from the Denver Rockets.
August 1Interstate highway I-80S is redesignated I-76. Over 500 route markers will be replaced in Colorado over the next two years.
The United States Army renames Fitzsimons Army Hospital in Aurora as Fitzsimons Army Medical Center.
Chogyam Trungpa establishes the Naropa Institute in Boulder.
April The City of Cañon City annexes the Town of East Cañon.
1973December 9The Denver Broncos defeat the San Diego Chargers 42 to 28 to assure their first winning season in their 14th year of play.
September 8Rebecca Ann King of Denver is crowned Miss America.
July 16Lieutenant Governor John Vanderhoof assumes office as the thirty-seventh Governor of the State of Colorado upon the resignation of Governor John Love to serve as Director of the United States Office of Energy Policy.
June 21The United States Supreme Court orders the complete desegregation of the Denver Public Schools in Keyes v. School District No. 1.
May 17The United States Atomic Energy Commission detonates three underground nuclear explosions in Colorado. Project Rio Blanco used the three nearly simultaneous blasts, each equivalent to 33,000 tonnes of TNT, to determine if nuclear explosions could be used to extract natural gas from sandstone deposits.
March 8Governor John Love dedicates the first bore of the Eisenhower Tunnel taking Interstate 70 under the Continental Divide of the Americas, the highest point on the Interstate Highway System.
January 3Pat Schroeder of Denver takes her seat in the United States House of Representatives as Colorado's first woman delegate to the U.S. Congress. Congresswoman Schroeder will represent Colorado's 1st congressional district for 24 years.
1972November 15Denver withdraws its offer to host the 1976 Winter Olympics, the first and only host city to reject an awarded Olympic Games.
November 7Colorado voters reject a $5 million bond issue to fund the 1976 Winter Olympics.
September 10Frank Shorter of Boulder wins the Men's Marathon at the Games of the XX Olympiad in Munich.
1971October 3The United States Department of Transportation opens the High Speed Ground Test Center east of Pueblo.
May 19The Denver Art Museum opens its Gio Ponti designed North Tower.
1970October 23The final segment of I-270 is opened, completing the 5.2-mile (8.4 km) Interstate Highway I-270.
September 20The Denver Broncos defeat the Buffalo Bills 25 to 10 in their first game as a National Football League franchise.
April 13An oxygen tank exploded on the Apollo 13 space flight to the moon. The three-man crew, including Command Module Pilot Jack Swigert of Denver, managed to fly safely back to Earth four days later.
April 1The 1970 United States Census enumerates the population of the State of Colorado, later determined to be 2,207,259, an increase of 25.85% since the 1960 United States Census. Colorado becomes the 30th most populous of the 50 U.S. states and gains a 5th Congressional District.

1960s
YearDateEvent
1969December 14The Denver Broncos defeat the Cincinnati Bengals 27 to 16 in their last game as an American Football League franchise. The Broncos finish the ten AFL seasons with a record of 39 wins, 97 losses, and 4 ties.
OctoberThe John Denver debut album Rhymes & Reasons is released.
September 21The final 21-mile (34 km) segment of Interstate Highway I-25 south of Walsenburg opens to traffic, completing the entire 305.040-mile (490.914 km) length of I-25 in Colorado.
September 10The United States Atomic Energy Commission detonates the first nuclear explosion in Colorado. Project Rulison used the underground blast, equivalent to 40,000 tonnes of TNT, to determine if nuclear explosions could be used to extract natural gas from shale gas deposits.
August 20U.S. President Richard Nixon signs An Act to provide for the establishment of the Florissant Fossil Beds National Monument in the State of Colorado.[1][2]
The City of Wheat Ridge in eastern Jefferson County incorporates.[3]
July 1The Colorado General Assembly creates the Regional Transportation District to promote public transportation in the Denver metropolitan area.
June 24The City of Lakewood in eastern Jefferson County incorporates.[3]
May 27The United States Department of Agriculture creates Comanche National Grassland and Pawnee National Grassland.[6]
May 12The International Olympic Committee selects Denver to host the XII Olympic Winter Games in 1976.
May 11A plutonium fire in Building 776/777 of the Atomic Energy Commission Rocky Flats Plant contaminates the plant near Arvada in the most expensive U.S. industrial accident to date.
1968December 13United States Secretary of Transportation Alan Boyd announces the selection of 1,472.5 miles (2369.8 km) of additional highway routes for the Interstate Highway System, including the 5.6-mile (9.0 km) extension of Interstate Highway I-80S from I-25 to I-70.
December 2U.S. President Lyndon B. Johnson signs An Act to establish a national trails system, and for other purposes, creating the National Trails System.
March 15Construction begins on the first bore of the Straight Creek Tunnel designed to route Interstate Highway I-70 under the Continental Divide.
February 10Peggy Fleming wins the Olympic gold medal in Women's Figure Skating at the X Olympic Winter Games in Grenoble.
1967October 15The Denver Rockets defeat the Anaheim Amigos 110 to 105 in their first game in the new American Basketball Association.
September 17The Denver-Boulder Turnpike becomes the first public toll road in the United States to pay for itself and becomes a freeway. The turnpike becomes a portion of the westward extension of federal highway route US-36 from Denver to Estes Park.
September 5The United States Fish and Wildlife Service establishes the Arapaho National Wildlife Refuge.
August 5The Denver Broncos defeat the Detroit Lions 13 to 7 to become the first American Football League team to defeat a National Football League team.
1966October 19Blue Mesa Dam on the Gunnison River in Gunnison County is completed.
January 1Air Force Systems Command turned the Cheyenne Mountain Combat Operations Center over to NORAD.[7]
1965December 12Interstate Highway I-270 construction begins in Denver.
July 25The United States Fish and Wildlife Service establishes the Browns Park National Wildlife Refuge.
June 16A flash flood on the South Platte River kills 28 people and inflicts over $500 million in damage.
March 26The last Titan I ICBM of the former Lowry Bombing and Gunnery Range was taken off alert status (all Titan 1s were in storage by April 18).[8]
February 6The National Park Service creates the Curecanti National Recreation Area.[2]
1964August 26The British band The Beatles perform at Red Rocks Amphitheatre near Morrison.
July 3The Robert Ward opera The Lady from Colorado premieres at the Central City Opera.
June 11The musical film The Unsinkable Molly Brown premieres in Denver.
MayConstruction of Interstate Highway I-225 begins in Aurora.
Stapleton Airfield in Denver is renamed Stapleton International Airport.
1963DecemberDillon Dam on the Blue River in Summit County is completed.
SeptemberEminent nuclear physicist Edward Condon joins the faculty of the University of Colorado.
July 25The United States Fish and Wildlife Service establishes the Alamosa National Wildlife Refuge.
March 1Dr. Thomas Starzl performs the world's first liver transplant at the University of Colorado Hospital in Denver.
January 8John Love assumes office as the thirty-sixth Governor of the State of Colorado.
1962November 15Three Atlas missile sites of Warren Air Force Base begin operation in Colorado (eventually 8 sites at Keoto, 5 at Padroni, 8 at Peetz, 8 at Stoneham, etc.)
May 24Astronaut Scott Carpenter from Boulder becomes the fourth person to orbit the Earth.
April 24The first of a series of minor earthquakes emanating from a region below the United States Army Rocky Mountain Arsenal near Denver is recorded. The earthquakes are later tied to the injection of toxic fluids into a hazardous waste disposal well at the chemical weapons plant.
April 16United States Deputy Attorney General Byron White is appointed the 83rd Associate Justice of the Supreme Court of the United States. White will serve on the court for 31 years.
1961July 20Tunneling begins for the NORAD bunker (the plan for a Denver Sector bunker had been cancelled in 1959, and the SAC bunker near Cripple Creek planned for 1965 was cancelled in 1963.)
June The Town of Broomfield incorporates.[3]
1960November 3The Meredith Willson musical The Unsinkable Molly Brown opens at the Winter Garden Theatre.
September 9The Denver Broncos defeat the Boston Patriots 13 to 10 in the very first American Football League game.
August 3Dave Rearick and Bob Kamps become the first climbers to surmount The Diamond on the east face of Longs Peak.
June 3U.S. President Dwight D. Eisenhower signs An Act Authorizing the establishment of a national historic site at Bent's Old Fort, near La Junta, Colorado, creating Bent's Old Fort National Historic Site.[2]
springInterstate 70 in Colorado construction begins near Idaho Springs.
April 1The 1960 United States Census enumerates the population of the State of Colorado, later determined to be 1,753,947, an increase of 32.36% since the 1950 United States Census. Colorado becomes the 33rd most populous of the 50 U.S. states.
February 9Brewer Adolph Coors III is murdered in a foiled kidnap attempt near his home in Bear Creek Canyon west of Denver.

1950s
YearDateEvent
1959July 2The Town of Columbine Valley incorporates.[3]
June 3The first class of the United States Air Force Academy graduates.
September 1Lowry Missile Site Number 1 construction begins southeast of Denver for a Titan I launch complex--Martin Missile Test Site 1 construction at Waterton Canyon had begun in April (alert status ended on March 26, 1965).
January 22The Adolf Coors Company of Golden introduces the aluminum beer can.
1958December 10Edward Lawrie Tatum is the 1st Colorado native to win the Nobel Prize for his 1937 metabolism work at Stanford University with George Wells Beadle.
August The Town of Bow Mar incorporates.[3]
Construction of Interstate Highway I-80S begins in northeastern Colorado (designated I-76 on August 1, 1974.)
May 12Canada and the United States establish the North American Air Defense Command (NORAD) to be headquartered at Ent Air Force Base.
1957October 18United States Secretary of Commerce Sinclair Weeks announces a 547-mile (880 km) western extension of Interstate 70 from Interstate 25 in Denver to Interstate 15 in Utah. The highway extension will require burrowing under the Continental Divide of the Americas.
September 11A plutonium fire in Building 71 of the Atomic Energy Commission Rocky Flats Plant contaminates the plant and releases radioactive plutonium into the air near Denver.
January 8Steve McNichols assumes office as the thirty-fifth Governor of the State of Colorado.
1956November 10Professor George Gamow (Георгий Антонович Гамов) of the University of Colorado is awarded the 1956 UNESCO Kalinga Prize.
October 15The Denver Public Library dedicates the new central library at the Denver Civic Center
September 22The Town of Boone incorporates.[3]
July 7The Douglas Moore opera The Ballad of Baby Doe premieres at the Central City Opera.
1955NovemberMonument Valley Freeway construction begins in Colorado Springs (later incorporated as part of I-25).
September 24U.S. President Dwight Eisenhower suffers an acute myocardial infarction in Denver. The President is treated at Fitzsimons Army Hospital in Aurora for several weeks.
September 11Sharon Kay Ritchie is the 1st Miss Colorado crowned Miss America (cf. Marilyn Van Derbur in 1957, Rebecca Ann King in 1973).
July 11The first class of 306 cadets of the United States Air Force Academy are sworn in at Lowry Air Force Base in Denver.
January 11Ed Johnson assumes office again as the thirty-fourth Governor of the State of Colorado.
January 3Gordon L. Allott takes his seat in the United States Senate. He will serve as a U.S. Senator from Colorado for 18 years.
1954June 24The United States Air Force selects an area north of Colorado Springs as the site for the United States Air Force Academy.
1953June 15The Town of Fraser incorporates.[3]
spring The Summer White House for U.S. President Dwight Eisenhower is established at Lowry Air Force Base through 1955.
1952December 18The Town of Commerce incorporates.[3]
September 3The United States Fish and Wildlife Service establishes the Monte Vista National Wildlife Refuge.
July 18Denver television station KFEL-TV (analog channel 2) begins the first television broadcasts in Colorado.
May 19The Town of Glendale incorporates.[3]
January 19The Denver-Boulder Turnpike opens to traffic.
1951July 10Construction of the United States Atomic Energy Commission Rocky Flats Plant begins 15 miles (24 km) northwest of Denver.
January 9Dan Thornton assumes office as the thirty-third Governor of the State of Colorado.
January 3Byron G. Rogers of Denver takes his seat in the United States House of Representatives. Congressman Rogers will represent Colorado's 1st congressional district for 20 years.
1950August 28U.S. President Harry S. Truman issues a Public Land Order creating Manti-La Sal National Forest.[6]
August 3U.S. President Harry S. Truman signs An Act to abolish the Wheeler National Monument, in the State of Colorado, and to provide for the administration of the lands contained therein as a part of the national forest within which such national monument is situated, and for other purposes. The geologic area reverts to Rio Grande National Forest, and is now a part of the La Garita Wilderness.[1]
U.S. President Harry S. Truman signs An Act to abolish the Holy Cross National Monument, in the State of Colorado, and to provide for the administration of the lands contained therein as a part of the national forest within which such national monument is situated, and for other purposes. The monument reverts to White River National Forest, and is now a part of the Holy Cross Wilderness.[1]
April 15Lieutenant Governor Walter Johnson assumes office as the thirty-second Governor of Colorado upon the resignation of Governor Bill Knous to serve as a federal judge.
April 1The 1950 United States Census enumerates the population of the State of Colorado, later determined to be 1,325,089, an increase of 17.96% since the 1940 United States Census. Colorado becomes the 34th most populous of the 48 U.S. states.
March 6The Town of Campo incorporates.[3]
February 13Aspen hosts the FIS Alpine World Ski Championships 1950 at Ajax Mountain Ski Resort, the first World Ski Championships held outside Europe.

1940s
YearDateEvent
1949Construction begins on the Pueblo Freeway in Pueblo. The Pueblo Freeway will be incorporated into Interstate Highway I-25.
January 3Wayne N. Aspinall of Palisade takes his seat in the United States House of Representatives. Congressman Aspinall will represent Colorado's 4th congressional district for 24 years.
1948AugustConstruction begins on the Valley Highway in Denver. The Valley Highway will be incorporated into Interstate Highway I-25.
March 15The Town of Cokedale incorporates.[3]
1947Denver FM radio station KLZ-FM begins commercial broadcasting at 106.7 MHz in the new U.S. FM broadcast band.
December 9The Town of Artesia incorporates.[3]
January 14William Lee Knous assumes office as the thirty-first Governor of the State of Colorado.
1946December 14The Ajax Mountain Ski Area opens at Aspen with the world's longest chairlift.
1945September 10Mike the Headless Chicken survives an assassination attempt but loses his head near Fruita.
September 2World War II ends as the Empire of Japan formally surrenders.
July 19The battleship USS Colorado (BB-45) steams into Tokyo Bay for the invasion of Honshu.
The Town of Cherry Hills Village incorporates.[3]
May 8The war in Europe ends as the Greater German Empire formally surrenders.
springThe Colorado Springs Tent Camp was established between the east edge of Colorado Springs and Peterson Field. ("Ent Air Force Base" in 1949, "Ent Annex" in 1975).
January 12John Charles Vivian assumes office as the thirtieth Governor of the State of Colorado.
1942August 27The Granada War Relocation Center (Camp Amache) opens for Japanese-American internees (Governor Carr opposed the internments in July.)
June 30Rocky Mountain Arsenal construction begins near Denver for World War II chemical weapons.
April 28The United States Army opens the Army Air Base at the Colorado Springs Municipal Airport (the shared airfield is later designated Peterson Field).
AprilThe United States Army begins construction of Camp Hale near Tennessee Pass.
AprilLowry Field Number 2 construction begins east of Aurora—cantonment construction begins May 5, 1942 (later designated Buckley Field, Buckley Air National Guard Base in 1960, Buckley AFB in 2000).
January 6The United States Army announces the selection of Colorado Springs as the site of a major Army base (designated Camp Carson a few weeks later, Fort Carson on August 27, 1954).
1941December 11The United States declares war on the German Reich and the Italian Empire
December 8The United States declares war on the Empire of Japan and enters World War II.
June 15Rotary International celebrates the Grand Opening of Red Rocks Amphitheatre with 10,000 in attendance during their annual convention. An "informal dedication" was held the week before.
April 14The Town of East Cañon incorporates.[3]
MarchDenver Ordnance Plant construction begins after a 1940 land purchase and January 1941 contract with Remington Arms Company (cf. February 1942 construction of the Pueblo Ordnance Depot).
January 3Colorado's 2nd congressional district representative (William S. Hill) and Colorado's 3rd congressional district representative (John Chenoweth) are seated in the United States House of Representatives.
1940May 19The Town of Federal Heights incorporates.[3]
April 1The 1940 United States Census enumerates the population of the State of Colorado, later determined to be 1,123,296, an increase of 8.45% since the 1930 United States Census. Colorado remains the 33rd most populous of the 48 U.S. states.

1930s
YearDateEvent
1939June 15The Town of Dove Creek incorporates.[3]
January 10Ralph Carr assumes office as the twenty-ninth Governor of the State of Colorado.
1938December 2U.S. President Franklin D. Roosevelt signs an executive order creating Colorado State Forest.
July 14U.S. President Franklin D. Roosevelt signs an executive order greatly enlarging Dinosaur National Monument.[1][2]
1937October 4Lowry Field construction begins with Works Progress Administration conversion of the Agnes Stipps Memorial Sanitorium for an Air Corps training base east of Denver (renamed Lowry AFB June 24, 1948.)
September 6The Will Rogers Shrine of the Sun is dedicated along the 1925 Cheyenne Mountain Highway.
July 22U.S. President Franklin D. Roosevelt signs An Act to create the Farmers' Home Corporation, to promote more secure occupancy of farms and farm homes, to correct the economic instability resulting from some present forms of farm tenancy, and for other purposes, also known as the Bankhead-Jones Farm Tenant Act.
February 7A donated rope tow begins operation at Berthoud Pass, creating Colorado's first public tow-assisted alpine skiing. Unfortunately, two skiers are killed in an avalanche the same day.
January 12Teller Ammons assumes office as the twenty-eighth Governor of the State of Colorado.
January 3Ed Johnson takes his seat in the United States Senate. He will serve as a U.S. Senator from Colorado for 18 years.
January 1Lieutenant Governor Ray Herbert Talbot assumes office as the twenty-seventh Governor of Colorado upon the resignation of Governor Ed Johnson to serve in the United States Senate.
1936September 14The Town of Garden City incorporates.[3]
May 9Members of Civilian Conservation Corps (CCC) Company 1848 at Morrison Camp SP-13-C in Red Rocks Park cease work on all other projects in preparation for the construction of Red Rocks Amphitheatre.
1935March 7The body of Elizabeth "Baby Doe" Tabor is found frozen to death in her cabin near the Matchless Mine in Lake County.
1934May 17The Dotsero Cutoff of 38.1 miles (61.3 km) in Colorado reduces the Denver-Salt Lake City railroad route by 173 miles (278 km).
1933March 2U.S. President Herbert Hoover issues a proclamation creating Black Canyon of the Gunnison National Monument.[1][2]
January 10Ed Johnson assumes office as the twenty-sixth Governor of the State of Colorado.
1932March 28U.S. President Herbert Hoover issues an executive order creating Roosevelt National Forest.[6]
March 17U.S. President Herbert Hoover issues a proclamation creating Great Sand Dunes National Monument.[1][2]
1930April 1The 1930 United States Census enumerates the population of the State of Colorado, later determined to be 1,035,791, an increase of 10.23% since the 1920 United States Census. Colorado remains the 33rd most populous of the 48 U.S. states.
January 22The Town of Bennett incorporates.[3]

1920s
YearDateEvent
1929NovemberThe City of Cañon City completes the Royal Gorge Bridge over the Arkansas River.
October 17Denver Municipal Airport opens (renamed Stapleton Airfield in 1944, Stapleton International Airport in 1964).
May 11U.S. President Herbert Hoover issues a proclamation creating Holy Cross National Monument.[1] (Abolished August 3, 1950.)
1928July 10The Town of Bethune incorporates.[3]
February 26The 6.2 mile (10.0 km) long Moffat Tunnel under the Continental Divide of the Americas opens as the world's longest railway tunnel.
1927January 11Billy Adams assumes office as the twenty-fifth Governor of the State of Colorado.
1926Spencer Penrose establishes his Cheyenne Mountain Zoo near the BROADMOOR.
1925JuneAdams State Normal School opens in Alamosa (named Adams State University in 2012).
January 13Clarence Morley assumes office as the twenty-fourth Governor of the State of Colorado.
1924June 2U.S. President Calvin Coolidge signs An Act To authorize the Secretary of the Interior to issue certificates of citizenship to Indians, also known as the Indian Citizenship Act of 1924, finally granting full United States Citizenship to all Native Americans born in the United States.[9]
March 11U.S. President Calvin Coolidge issues an executive order creating Grand Mesa National Forest.[6]
1923August 30The battleship USS Colorado (BB-45) is commissioned in New York Harbor.
March 2U.S. President Warren G. Harding issues a proclamation creating Hovenweep National Monument.[1][2]
January 9William Ellery Sweet assumes office as the twenty-third Governor of the State of Colorado.
1922March 10Denver radio station 9ZAF receives a commercial license as KLZ (AM 560 kHz), the first commercial radio station in Colorado.
1921October 10The Town of Crowley incorporates.[3]
July 21The Colorado River designation is extended to its Grand River tributary, which has its source in Colorado. Grand River namesakes (e.g., valley, county, lake, and city) remain unchanged.
June 3Flash floods on the Arkansas River and Fountain Creek kill 1500 people and inflict over $20 million of damage around Pueblo.
March 26The Town of Branson incorporates.[3]
1920December 5Douglas Fairbanks becomes the first Coloradoan to star in a major motion picture: silent film The Mark of Zorro.
JulyThe United States Army renames Army Hospital 21 in Aurora as Fitzsimons Army Hospital.
June 15The Town of Eckley incorporates.[3]
April 1The 1920 United States Census enumerates the population of the State of Colorado, later determined to be 939,629, an increase of 17.60% since the 1910 United States Census. Colorado becomes the 33rd most populous of the 48 U.S. states.
February 3The Town of Deer Trail incorporates.[3]

1910s
YearDateEvent
1919December 19U.S. President Woodrow Wilson issues a proclamation creating Yucca House National Monument.[1][2]
July 4Jack Dempsey of Manassa, Colorado, defeats Jess Willard in a bout at Toledo, Ohio for the World Heavyweight Boxing Championship.
June 10The Town of Calhan incorporates.[3]
1918November 11An armistice halts the Great War.
AutumnThe Denver Art Association becomes the Denver Art Museum.
September 23The Town of Crook incorporates.[3]
August 29The Town of Arriba incorporates.[3]
June 29The Broadmoor resort opens near Colorado Springs at the site of the Broadmoor Casino and adjacent to the c. 1900 Broadmoor Shooting Grounds.[10]
May 14Denver Mayor Robert W. Speer dies at home in Denver at age 62.
SpringConstruction of Army Hospital 21 begins in Aurora (named Fitzsimons Army Hospital in 1920, Fitzsimons Army Medical Center in 1974, closed 1999.)
1917May 5The Town of Fleming incorporates.[3]
April 17The Town of Estes Park incorporates.[3]
The Town of Cheraw incorporates.[3]
April 6The United States declares war on the German Empire and enters the Great War.
January 10William Frederick "Buffalo Bill" Cody dies in Denver at age 70.
January 9Julius Caldeen Gunter assumes office as the twenty-first Governor of the State of Colorado.
1916November 2The Town of Flagler incorporates.[3]
August 25U.S. President Woodrow Wilson signs An Act To establish a National Park Service, and for other purposes.[11]
July 1Lieutenant Dwight D. Eisenhower marries Mamie Doud in Denver.
January 29The Town of Eads incorporates.[3]
1915October 4U.S. President Woodrow Wilson issues a proclamation creating Dinosaur National Monument.[1][2]
March 4Colorado creates its 3rd Congressional District and its 4th Congressional District to replace its two At-large Congressional seats. These two congressional districts remain to the present.
January 26U.S. President Woodrow Wilson signs An Act to establish the Rocky Mountain National Park in the State of Colorado, and for other purposes.[2]
January 12George Alfred Carlson assumes office as the twentieth Governor of the State of Colorado.
1914April 28-29The Battle of Walsenburg is fought between strikers and the Colorado National Guard as part of the violence stemming from the Ludlow Massacre and Colorado Coalfield War.
April 20The Ludlow Massacre by the Colorado National Guard kills striking coal miners, 2 women, and 11 children.
1913December 1Denver's greatest snowfall ever begins. Denver receives a five-day accumulation of 45.7 inches (1161 mm), while Georgetown gets 86 inches (2184 mm).
March 8The State of Colorado creates Alamosa County from portions of Costilla and Conejos counties.[4]
January 14Elias M. Ammons assumes office as the nineteenth Governor of the State of Colorado.
1912April 26The Colorado Mountain Club is founded in Denver.
April 15The RMS Titanic strikes an iceberg and sinks. Margaret Brown of Denver is hailed as a heroine by survivors.
March 18The Town of Gilcrest incorporates.[3]
1911NovemberThe Daniels & Fisher Tower opens in Denver.
July 17The Mountain States Telephone and Telegraph Company is formed in Denver.
June 29U.S. President William Howard Taft issues a proclamation creating Durango National Forest.[6]
May 29The State of Colorado creates Crowley County from a portion of Otero County.[4]
May 24U.S. President William Howard Taft issues a proclamation creating Colorado National Monument.[1]
May 10Scottish operatic soprano Mary Garden sings in concert at the Park of the Red Rocks near Morrison.
February 27The State of Colorado creates Moffat County from a portion of Routt County.[4]
1910December 19The Town of Crawford incorporates.[3]
July 1U.S. President William Howard Taft signs an executive order creating Colorado National Forest (renamed Roosevelt National Forest on March 28, 1932.)
May 18The Town of Blanca incorporates.[3]
April 1The 1910 United States Census enumerates the population of the State of Colorado, later determined to be 799,024, an increase of 48.05% since the 1900 United States Census. Colorado becomes the 32nd most populous of the 46 U.S. states and gains a 4th Congressional seat.
February 15The Denver Public Library dedicates its new library building.

1900s
YearDateEvent
1909July 17The Shoshone Hydroelectric Generating Station begins transmitting electricity from Glenwood Canyon to the Denver area over the Shoshone Transmission Line.
April 26U.S. President William Howard Taft issues executive orders creating Sopris National Forest.[6]
March 16U.S. President William Howard Taft issues executive orders creating La Sal National Forest.[6]
May 5The State of Colorado creates Jackson County from the western portion of Larimer County.[4]
March 4Edward T. Taylor takes his seat in the United States House of Representatives. Congressman Taylor will represent Colorado in the U.S. House for more than 32 years.
January 19The Denver, Northwestern and Pacific Railway reaches Steamboat Springs.
January 12John F. Shafroth assumes office as the eighteenth Governor of the State of Colorado.
1908December 7U.S. President Theodore Roosevelt issues a proclamation creating Wheeler National Monument, the first Colorado National Monument.[1] (Abolished August 3, 1950.)
October 8The Town of Firestone incorporates.[3]
September 23The Town of Dacono incorporates.[3]
September 9The Town of Frederick incorporates.[3]
July 22The Town of Collbran incorporates.[3]
July 15The Town of Craig incorporates.[3]
July 10The Democratic National Convention meeting in Denver nominates William Jennings Bryan for President of the United States
July 1U.S. President Theodore Roosevelt issues executive orders creating Rio Grande National Forest, Pike National Forest, Cochetopa National Forest, Arapaho National Forest, and Battlement National Forest.[6]
The Colorado Museum of Natural History opens its new building in Denver City Park.
June 25U.S. President Theodore Roosevelt issues executive orders creating Routt National Forest and Hayden National Forest.[6]
1907May 2The Town of Cedaredge incorporates.[3]
March 4The Town of Fletcher changes its name to the Town of Aurora.
March 1U.S. President Theodore Roosevelt issues a proclamation creating the Las Animas Forest Reserve.[6]
February 2U.S. President Theodore Roosevelt issues a proclamation creating the Ouray Forest Reserve.[6]
January 18The Town of Center incorporates.[3]
January 8Henry Augustus Buchtel assumes office as the seventeenth Governor of the State of Colorado.
1906August 18The Town of Bayfield incorporates.[3]
August 1The Argentine Central Railway reaches the 13,587-foot (4141 m) summit of Mount McClellan.
June 29U.S. President Theodore Roosevelt signs An Act Creating the Mesa Verde National Park.[2]
June 8U.S. President Theodore Roosevelt signs An Act For the preservation of American antiquities, also known as the Antiquities Act of 1906, giving the President of the United States the authority to create national monuments on federal lands to protect significant natural, cultural, or scientific features.[12]
February 24U.S. President Theodore Roosevelt issues a proclamation creating the Fruita Forest Reserve.[6]
January 29The first Western Livestock Show opens in Denver. The show will become the National Western Stock Show, Rodeo and Horse Show.
January 25U.S. President Theodore Roosevelt issues a proclamation creating the La Sal Forest Reserve.[6]
1905August 25U.S. President Theodore Roosevelt issues a proclamation creating the Holy Cross Forest Reserve.[6]
July 27The Town of Genoa incorporates.[3]
June 14U.S. President Theodore Roosevelt issues a proclamation creating the Uncompahgre Forest Reserve.[6]
June 13U.S. President Theodore Roosevelt issues proclamations creating the Cochetopa Forest Reserve and the Montezuma Forest Reserve.[6]
June 12U.S. President Theodore Roosevelt issues proclamations creating the Park Range Forest Reserve and the Wet Mountains Forest Reserve.[6]
June 3U.S. President Theodore Roosevelt issues a proclamation creating the San Juan Forest Reserve.[6]
May 12U.S. President Theodore Roosevelt issues proclamations creating the Gunnison Forest Reserve, the Leadville Forest Reserve, and the Pikes Peak Forest Reserve.[6]
May 9The first water flows over the spillway of the new Cheesman Dam on the South Platte River in Jefferson and Douglas counties. The dam is the world's tallest at 221 feet (67.3 m).
April 5The Town of Eagle incorporates.[3]
March 17March 17 becomes Colorado's day with three governors as Alva Adams, James Hamilton Peabody, and Jesse Fuller McDonald sequentially serve as the Governor of the State of Colorado.
January 19The armored cruiser USS Colorado (ACR-7) is commissioned at Philadelphia.
January 10Alva Adams assumes office again as the fourteenth Governor of the State of Colorado.
1904November 5The Town of Edgewater incorporates.[3]
August 24The Town of Arvada incorporates.[3]
June 1Robert W. Speer assumes office as the Mayor of the City and County of Denver.
April 11The Town of Bergdorf incorporates.[3]
1903May 9The Town of Englewood incorporates.[3]
May 5The Town of Fletcher incorporates.[3] Changes name to the Town of Aurora on March 4, 1907.
April 23The Town of Fountain incorporates.[3]
April 11The State of Colorado changes the name of South Arapahoe County back to Arapahoe County.[4]
January 13James Hamilton Peabody assumes office as the thirteenth Governor of the State of Colorado.
1902November 15After a prolonged court battle, the State of Colorado splits Arapahoe County into three new counties: the City and County of Denver, South Arapahoe County, and Adams County.[4]
November 10The Town of Cortez incorporates.[3]
July 18The Denver, Northwestern and Pacific Railway incorporates in Denver to construct a direct rail line to Salt Lake City via a tunnel under the Continental Divide.
June 28U.S. President Theodore Roosevelt issues a proclamation creating the White River Forest Reserve.[6]
April 11U.S. President Theodore Roosevelt issues a proclamation creating the San Isabel Forest Reserve.[6]
January 24The Town of Crestone incorporates.[3]
1901August 26The Town of Basalt incorporates.[3]
January 8James Bradley Orman assumes office as the twelfth Governor of the State of Colorado.
1900December 6The Colorado Museum of Natural History in Breckenridge is incorporated.
August 25The Town of Fowler incorporates.[3]
July 19The Town of Dolores incorporates.[3]
April 1The 1900 United States Census enumerates the population of the State of Colorado, later determined to be 539,700, an increase of 30.60% since the 1890 United States Census. Colorado becomes the 31st most populous of the 45 U.S. states and gains a 3rd Congressional seat.

1890s
YearDateEvent
1899June 1Nikola Tesla (Никола Тесла) begins research on the wireless transmission of power at his new laboratory in Colorado Springs.
March 23The State of Colorado creates Teller County from portions of El Paso and Fremont counties.[4]
January 10Charles Spalding Thomas assumes office as the eleventh Governor of the State of Colorado.
1898December 10The United States of America and the Kingdom of Spain sign the Treaty of Paris of 1898 to end the Spanish–American War.
August 12The United States of America and the Kingdom of Spain sign a Protocol of Peace.
April 23The Kingdom of Spain declares war on the United States of America. The United States declares war on Spain two days later.
April 19U.S. Senator Henry M. Teller of Colorado offers the Teller Amendment to a Joint Resolution of Congress to ensure that the United States will not establish permanent control over Cuba after any conflict with Spain.
1897January 12Alva Adams assumes office again as the tenth Governor of the State of Colorado.
1896November 7The Denver Zoo opens.
1895November 15The Town of Del Norte incorporates.[3]
October 28Harry Heye Tammen and Frederick Gilmer Bonfils purchase the Evening Post of Denver for $12,500 (renamed Denver Evening Post November 3, The Denver Post January 1, 1901).
January 8Albert Washington McIntire assumes office as the ninth Governor of the State of Colorado.
1894July 1The Florence and Cripple Creek Railroad reaches Cripple Creek.
April 18The Town of Fruita incorporates.[3]
March 18Denver Union Station is extensively damaged by fire.
March 14The Denver City Police and Arapahoe County Deputy Sheriffs barricade Denver City Hall to prevent the Colorado State Infantry from seizing the building in the City Hall War of 1894.
January 10The Town of Aguilar incorporates.[3]
1893November 7Colorado becomes the second U.S. state to grant women suffrage and the first state where the men voted to give women the right to vote.
November 1U.S. President Grover Cleveland signs the Repeal of the Sherman Silver Purchase Act (enacted July 14, 1890), but the repeal fails to halt the Panic of 1893 and plunges Colorado into a massive economic depression.
July 22Katharine Lee Bates visits the summit of Pikes Peak and writes the poem America the Beautiful.
March 27The State of Colorado creates Mineral County from portions of Hinsdale, Rio Grande, and Saguache counties.[4]
January 10Davis Hanson Waite assumes office as the eighth Governor of the State of Colorado.
1892December 24U.S. President Benjamin Harrison issues a proclamation creating the Battlement Mesa Forest Reserve.[6]
December 5The Town of Eaton incorporates.[3]
December 9U.S. President Benjamin Harrison issues a proclamation creating the South Platte Forest Reserve.[6]
AugustPolitical supporters of Grover Cleveland found the Evening Post in Denver with $50,000.
Henry Perky of Denver develops a machine for making "little whole wheat mattresses", later called shredded wheat.
June 23U.S. President Benjamin Harrison issues a proclamation creating the Plum Creek Timber Land Reserve.[6]
June 9The Town of Cripple Creek incorporates.[3]
May 19The Town of Creede incorporates.[3]
February 11U.S. President Benjamin Harrison issues a proclamation creating the Pikes Peak Timber Land Reserve.[6]
1891October 16The Denver and Rio Grande Railroad reaches Creede.
U.S. President Benjamin Harrison issues a proclamation creating the White River Plateau Timber Land Reserve, the second United States National Forest.[6]
July 1The Broadmoor Casino opens near Colorado Springs.
March 3U.S. President Benjamin Harrison signs An act to repeal timber-culture laws, and for other purposes, also known as the Forest Reserve Act of 1891, giving the President of the United States the authority to create protected national forests on federal lands.[13]
January 13John Long Routt assumes office as the seventh Governor of the State of Colorado.
1890October 22The Manitou and Pike's Peak Railway completes the rack and pinion line to the 14,115-foot (4,302 m) summit of Pikes Peak.
October 20Rancher Robert Miller Womack discovers a rich gold lode along Cripple Creek near Pikes Peak. The Cripple Creek Mining District will produce more than 730 tonnes of gold, the most of any Rocky Mountain district.
October 9The Town of Elizabeth incorporates.[3]
July 4The Colorado State Capitol cornerstone is placed for the new building on Brown's Bluff in Denver.
May 14The Town of Cheyenne Wells incorporates.[3]
April 1The 1890 United States Census enumerates the population of the State of Colorado, later determined to be 413,249, an increase of 112.66% since the 1880 United States Census. Colorado becomes the 31st most populous of the 44 U.S. states and gains a 2nd Congressional District.
January 18The Town of De Beque incorporates.[3]
January 15The Town of Fort Lupton incorporates.[3]

1880s
YearDateEvent
1889December 29The Town of Antonito incorporates.[3]
June 24The Denver and Rio Grande Railroad reaches Lake City.
JuneThe City of Denver establishes the Denver Public Library.
April 16The State of Colorado creates Baca County from a portion of Las Animas County, and Montezuma County from a portion of La Plata County.[4]
April 11The State of Colorado creates Kiowa, Kit Carson, Lincoln, and Prowers counties from portions of Bent and Elbert counties.[4]
April 9The State of Colorado creates Sedgwick County from a portion of Logan County.[4]
March 27The State of Colorado creates Phillips County from a portion of Logan County.[4]
March 25The State of Colorado creates Cheyenne County from portions of Elbert and Bent counties, Otero County from a portion of Bent County, and Rio Blanco County from a portion of Garfield County.[4]
March 15The State of Colorado creates Yuma County from a portion of Washington County.[4]
February 19The State of Colorado creates Morgan County from a portion of Weld County.[4]
January 8Job Adams Cooper assumes office as the sixth Governor of the State of Colorado.
1888December 18Richard Wetherill and Charlie Mason find the Cliff Palace on Mesa Verde.
August 28The Town of Berthoud incorporates.[3]
April 26The Town of Carbondale incorporates.[3]
April 9The Denver, Texas and Fort Worth Railroad begins service between Denver and Fort Worth.
January 12The Town of Burlington incorporates.[3]
January 1The Missouri Pacific Railroad begins service between Pueblo, Kansas City, and Saint Louis.
1887November 5The Atchison, Topeka and Santa Fe Railroad reaches Denver.
October 31The United States Army establishes Fort Logan southwest of Denver (transferred from the Army Air Service Command to the Veterans Administration in May 1946.)[14][15][16]
October 28The Denver and Rio Grande Railroad reaches Aspen.
October 6The Denver and Rio Grande Railroad reaches Glenwood Springs via Glenwood Canyon.
September 22The Town of Akron incorporates.[3]
September 13The Town of Florence incorporates.[3]
September 3The Colorado Midland Railroad begins service between Colorado City and Leadville via Buena Vista and Hagerman Tunnel under the Continental Divide of the Americas.
September 1The Town of Brighton incorporates.[3]
June 15The Town of Fort Morgan incorporates.[3]
February 25The State of Colorado creates Logan County from a portion of Weld County.[4]
February 9The State of Colorado creates Washington County from a portion of Weld County.[4]
January 11Alva Adams assumes office as the fifth Governor of the State of Colorado.
1886July 12The City of Blackhawk incorporates.[3]
June 19The Town of Colorado Springs incorporates.[3] Colorado Springs is the seat of El Paso County.
June 12The City of Central incorporates.[3] Central City is the seat of Gilpin County.
1885November 15The Town of Silverton incorporates.[3] Silverton is the seat of San Juan County.
The Town of Pueblo incorporates.[3] Pueblo is the seat of Pueblo County.
The Town of Greeley incorporates.[3] Greeley is the seat of Weld County.
The Town of Evans incorporates.[3]
The Town of Erie incorporates.[3]
April 14The State of Colorado creates Archuleta County from a portion of Conejos County.[4]
January 13Benjamin Harrison Eaton assumes office as the fourth Governor of the State of Colorado.
1884November 24The Town of Brush incorporates.[3]
April The Georgetown, Breckenridge and Leadville Railway reaches SilverPlume via the Georgetown Loop.
1883March 2The State of Colorado creates San Miguel County from a portion of San Juan County, and reverts the name of Uncompaghre County back to Ouray County.[4]
March 1U.S. Senator Horace Tabor of Colorado marries Elizabeth "Baby Doe" McCourt in Washington, D.C.
February 27The Colorado General Assembly renames Ouray County as Uncompaghre County.[4]
February 14The State of Colorado creates Mesa County from a portion of Gunnison County.[4]
February 12The Town of Fort Collins incorporates.[3] Fort Collins is the seat of Larimer County.
February 11The State of Colorado creates Eagle County from a portion of Summit County, and Delta and Montrose counties from portions of Gunnison County.[4]
February 10The State of Colorado creates Garfield County from a portion of Summit County.[4]
January 26The Town of Dillon incorporates.[3]
January 9James Benton Grant assumes office as the third Governor of the State of Colorado.
1882December 19The Denver and Rio Grande Railroad reaches the Colorado-Utah Territory border west of Grand Junction.
November 21The Denver and Rio Grande Railroad reaches Grand Junction.
November 7An earthquake estimated at 6.2 Mfa affects the Denver area with a maximum Mercalli intensity of VII (Very strong). The quake causes minor damage in Colorado and southern Wyoming and is the most intense in Colorado recorded history.[17]
October 24The Town of Delta incorporates.[3]
September 8The Denver and Rio Grande Railroad reaches Montrose.
September 6The Denver, South Park and Pacific Railroad reaches Gunnison via the Alpine Tunnel under the Continental Divide of the Americas.
July 8The Denver and Rio Grande Railroad reaches Silverton.
June 26The Chicago, Burlington and Quincy Railroad reaches Denver.
May 7The Denver and New Orleans Railroad begins service between Denver and Pueblo.
May 6U.S. President Chester A. Arthur signs the Chinese Exclusion Act banning Chinese immigration to the United States and denying citizenship to all persons of Chinese ancestry.
April 18U.S. President Chester A. Arthur appoints Henry Moore Teller as U.S. Secretary of the Interior. Teller is the first Coloradan to serve in the Cabinet of the United States..
April 13Oscar Wilde visits Leadville and later writes, "They afterwards took me to a dancing saloon where I saw the only rational method of art criticism I have ever come across. Over the piano was printed a notice : — PLEASE DO NOT SHOOT THE PIANIST. HE IS DOING HIS BEST."
April 12The Town of Empire incorporates.[3]
February 11The Town of Coal Creek incorporates.[3]
1881November 24The Denver and Rio Grande Railroad reaches Crested Butte.
November 8The City of Denver is made the permanent capital of the State of Colorado by a state referendum.
August 8The Denver and Rio Grande Railroad reaches Gunnison.
July 27The Denver and Rio Grande Railroad reaches Durango.
June 1Denver Union Station opens.
May 17The Town of Castle Rock incorporates.[3]
April 27The Town of Durango incorporates.[3]
April 1The Town of Aspen incorporates.[3]
March 4The State of Colorado creates Dolores County from a portion of Ouray County.[4]
February 23The State of Colorado creates Pitkin County from a portion of Gunnison County.[4]
February 21The Colorado Electric Company incorporates in Denver.
January 13The Town of Bonanza City incorporates.[3]
1880December 3The Town of Frisco incorporates.[3]
July 22The Denver and Rio Grande Railroad reaches Leadville. The first passenger train to Leadville carries former President Ulysses Grant, the man who brought Colorado statehood.
July 15The Town of Crested Butte incorporates.[3]
June 1The Denver and Rio Grande Railroad reaches the Colorado-New Mexico Territory border south of Antonito.
April 1The 1880 United States Census enumerates the population of the State of Colorado, later determined to be 194,327, an increase of 387% since the 1870 United States Census. Colorado becomes the 35th most populous of the 38 U.S. states.
March 27The Denver and Rio Grande Railway reaches a legal accommodation with the Atchison, Topeka and Santa Fe Railroad known as the Treaty of Boston.
March 3The Denver, South Park and Pacific Railroad reaches Buena Vista.
The Town of Breckenridge incorporates.[3]

1870s
YearDateEvent
1879November 8The Town of Buena Vista incorporates.[3]
September 1Colorado Agricultural College opens to students. The land-grant college is renamed Colorado State College of Agriculture and Mechanic Arts in 1935, and renamed Colorado State University in 1957.
JulyThe Colorado Historical Society is founded in Denver.
May 7The first passenger train passes through the Royal Gorge.
April 21The United States Supreme Court rules in the Royal Gorge War between the Denver and Rio Grande Railway and the Atchison, Topeka, and Santa Fe Railroad.
February 24The Denver Telephone Dispatch Company opens for business.
February 10The Colorado General Assembly abolishes Carbonate County after two days and splits its territory between a new Chaffee County and a renamed Lake County.[4]
February 8The Colorado General Assembly renames Lake County as Carbonate County.[4]
January 14Frederick Walker Pitkin assumes office as the second Governor of the State of Colorado.
1878December 7The Atchison, Topeka and Santa Fe Railroad reaches Raton Pass on the Santa Fe Trail, blocking the Denver and Rio Grande Railway's route to Santa Fe.
August 12The Town of Alamosa incorporates.[3]
June 26The Denver and Rio Grande Railway reaches Alamosa.
April 19The Royal Gorge War begins as a construction crew of the Atchison, Topeka and Santa Fe Railroad blocks a crew of the Denver and Rio Grande Railway from building into the Royal Gorge.
May 22The Colorado Central Railroad reaches Central City.
January 1David May opens The Great Western Auction House and Clothing Store in Leadville.
1877September 16The Solid Muldoon is uncovered on Muldoon Hill near Beulah.
SeptemberDavid May, Jacob Holcombe, and Thomas Dean open a dry goods store in Leadville. The store will become the first component of The May Department Stores Company.
August 13The Colorado Central Railroad reaches Georgetown.
March 9The State of Colorado creates Custer County from a portion of Fremont County, and Gunnison County from a portion of Lake County.[4]
January 29The State of Colorado creates Routt County from a portion of Grand County.[4]
January 18The State of Colorado creates Ouray County from portions of Hinsdale and Lake counties.[4]
1876November 1The Colorado General Assembly convenes for the first time.
October 3Voters of the new State of Colorado elect Territorial Governor John Long Routt as their first State Governor, Henry Moore Teller and Jerome Bunty Chaffee as their first U.S. Senators, and James Burns Belford as their first U.S. Representative.
August 1U.S. President Ulysses S. Grant issues Proclamation 230: Admission of Colorado into the Union.[18] The Territory of Colorado becomes the State of Colorado, the 38th U.S. state.
July 4The Territory of Colorado celebrates the Centennial of the United States of America while still reeling from the defeat of Lieutenant Colonel George Armstrong Custer and the 7th Cavalry Regiment at the Battle of the Little Bighorn on June 26.
July 1Voters of the Territory of Colorado approve the proposed Constitution of the State of Colorado by a vote of 15,443 to 4,039.
March 14The Colorado Constitutional Convention[19] adopts the proposed Constitution of the State of Colorado[20]
The Territory of Colorado establishes the University of Colorado at Boulder.
February 29The Atchison, Topeka and Santa Fe Railroad reaches Pueblo.
January 31The Territory of Colorado creates San Juan County from a portion of Lake County.[4]
1875October 25The Colorado Constitutional Convention convenes in Denver to write a state constitution.
October 5Ulysses S. Grant becomes the first President of the United States to visit the Colorado Territory.
March 29U.S. President Ulysses S. Grant appoints John Long Routt to be the eighth (and last) Governor of the Territory of Colorado.
March 3U.S. President Ulysses S. Grant signs An Act to enable the people of Colorado to form a constitution and State government, and for the admission of the said State into the Union on an equal footing with the original States.[21]
U.S. President Ulysses S. Grant signs the Page Act limiting the immigration of Asians into the United States.
1874August 14Members of the Wheeler Survey make the first recorded ascent of Blanca Peak in the San Luis Valley.
July 6The Denver and Rio Grande Railway reaches Cañon City.
June 19U.S. President Ulysses S. Grant appoints Edward M. McCook a second time to be the seventh Governor of the Territory of Colorado.
February 10The Territory of Colorado creates Hinsdale, La Plata, and Rio Grande counties from portions of Conejos, Costilla, and Lake counties.[4]
February 9The Territory of Colorado purchases the Territorial School of Mines in Golden from the Episcopal Church for $5,000.
The Territory of Colorado abolishes Platte County after organizers fail to secure voter approval. The territory of the county is returned to Weld County.[4]
February 6The Territory of Colorado abolishes Greenwood County and divides its territory between Elbert County and Bent County.[4]
February 3The Territory of Colorado creates Elbert County from a portion of Douglas County, and Grand County from a portion of Summit County.[4]
1873December 2The Town of Alma incorporates.[3]
September 17The Denver and Boulder Valley Railroad reaches Boulder.
June 16The Town of Walsenburg incorporates.[3] Walsenburg is the seat of Huerfano County.
April 4U.S. President Ulysses S. Grant appoints Samuel Hitt Elbert to be the sixth Governor of the Territory of Colorado.
1872December 15The Colorado Central Railroad reaches Black Hawk.
November 15The Town of Fairplay incorporates.[3] Fairplay is the seat of Park County.
October 9The first Southern Colorado Agricultural and Industrial Exposition is held in Pueblo. The exposition will become the Colorado State Fair.
October 2The Denver, South Park and Pacific Railroad incorporates in Denver to build a narrow gauge railway through South Park to the Gunnison River and the Utah Territory.
June 15The Denver and Rio Grande Railway reaches Pueblo.
April 3The Town of Cañon City incorporates.[3] Cañon City (also spelled Canyon City and Canon City) is the seat of Fremont County.
February 11The Territory of Colorado creates Platte County from the eastern portion of Weld County.[4]
1871November 4The City of Boulder incorporates.[3] Boulder City is the seat of Boulder County.
October 27The Denver and Rio Grande Railway is completed from Denver to the new town of Colorado Springs, bypassing Colorado City 5 mi (8.0 km) to the west.
January 2The City of Golden incorporates.[3] Golden City is the former territorial capital and the seat of Jefferson County.
1870October 27The Denver and Rio Grande Railway incorporates in Denver. The company plans to build a narrow gauge railway from Denver south to Santa Fe, New Mexico Territory; El Paso, Texas; and on to Mexico City.
September 22The Colorado Central Railroad reaches Golden from Denver.
August 15The Kansas Pacific Railroad reaches Denver from Kansas City, Missouri, creating the first all-rail transcontinental route.
June 21The Denver Pacific Railroad reaches Denver from the Union Pacific mainline at Cheyenne, Wyoming Territory.
May 2Episcopal Bishop George Maxwell Randall begins construction of the Territorial School of Mines at Golden City.
April 1The 1870 United States Census enumerates the population of the Territory of Colorado, later determined to be 39,864, an increase of 16% since the 1860 United States Census. Colorado becomes the 3rd most populous of the nine U.S. territories.
February 11The Territory of Colorado creates Bent and Greenwood counties from expropriated Cheyenne and Arapaho tribal land and portions of Huerfano County.[4]

1860s
YearDateEvent
1869December 14Nathan Meeker, agricultural editor of the New York Tribune, appeals to readers of high moral character to help him build a utopian farming community between the Cache La Poudre River and the South Platte River in the Territory of Colorado. Meeker will name the community Greeley in honor of his publisher, Horace Greeley.
November 13The Denver Gas Company incorporates in Denver City.
August 19S.F. Sharpless and William M. Davis make the first recorded ascent of Mount Harvard, highest of the Collegiate Peaks.
July 4Deer Trail hosts the world's first organized rodeo.
 Surveyor O.N. Chaffee determines the eastern boundary of the Colorado Territory beginning from Julesburg.[22][23]
June 14U.S. President Ulysses S. Grant appoints Edward M. McCook to be the fifth Governor of the Territory of Colorado.
March 4Commanding General of the United States Army Ulysses S. Grant assumes office as the 18th President of the United States.
1868August 23A party led by John Wesley Powell makes the first recorded ascent of Longs Peak.
July 9The Fourteenth Amendment to the United States Constitution is ratified.
May 23Brigadier General Kit Carson dies at new Fort Lyon at age 58.
January 10Town of Georgetown incorporates. The Town of Georgetown is the only Colorado municipality still operating under its original charter from the Territory of Colorado.
1867December 9The Territory of Colorado votes to move the territorial capital from Golden City to Denver City, the seat of Arapahoe County.
November 18The Union Pacific Railroad reaches Julesburg and eventually will have 9 miles (14 km) of mainline in the Colorado Territory.
April 24U.S. President Andrew Johnson appoints Alexander Cameron Hunt to be the fourth Governor of the Territory of Colorado.
1866December 29The Territory of Colorado creates Saguache County from portions of Lake and Costilla counties.[4]
March 6Brigadier General Kit Carson takes command of Fort Garland in the San Luis Valley in an effort to make peace with the Ute Nation.
February 9The Territory of Colorado creates Las Animas County from a portion of Huerfano County.[4]
1865October 17U.S. President Andrew Johnson appoints Alexander Cummings of Pennsylvania to be the third Governor of the Territory of Colorado.
SeptemberThe (white male) voters of the Territory defeat a referendum for universal male suffrage by a vote of 476 to 4,192, denying the vote to Indians, Negros, Asians, as well as women.
July 18U.S. President Andrew Johnson demands that John Evans resign as the Governor of the Territory of Colorado following an investigation of the Sand Creek Massacre.
May 9U.S. President Andrew Johnson proclaims the end of the American Civil War.
April 15U.S. Vice President Andrew Johnson assumes office as the 17th President of the United States upon the assassination of Abraham Lincoln.
1864November 29Colonel (and the Reverend) John Chivington orders the murder of hundreds of Cheyenne and Arapaho people in the Sand Creek Massacre.
October 22The Union Army moves Camp Collins downstream to the present site of Fort Collins.
May 13A flash flood on Cherry Creek sweeps away most low-lying structures of Denver City and separates many residents from their local saloons and brothels.
March 3Governor John Evans and the Reverend John Chivington found Colorado Seminary in Denver City. The seminary will close in 1868, but reopen in 1880 as the University of Denver.
1863January 2The Boonville post office opens.
1862December 6The Black Hawk Point post office opens.
August 14The Territory of Colorado votes to move the territorial capital from Colorado City to Golden City, the seat of Jefferson County.
July 22The Union Army establishes Camp Collins near Colona.
July 7The second session of The Territory of Colorado convenes in Colorado City.
April 6Alferd Packer arrives at the Los Pinos Indian Agency in the Cochetopa Hills with no trace of his five companions. Upon questioning, Packer admits that he ate his companions.
March 28Colorado volunteers under the command of Colonel John P. Slough repulse Texas cavalry under the command of Lieutenant Colonel William Read Scurry at the Battle of Glorieta Pass. The battle effectively ends the Confederate New Mexico Campaign.
March 26U.S. President Abraham Lincoln appoints John Evans of Illinois to be the second Governor of the Territory of Colorado.
March 10Texas cavalry under the command of Brigadier General Henry Hopkins Sibley occupy Santa Fe in the Confederate New Mexico Campaign.
February 9Alferd Packer and five companions leave the camp of Ouray on the Uncompahgre River bound for the Cochetopa Hills.
1861November 7The Territory of Colorado reincorporates the City of Denver, Auraria, and Highland as the City of Denver (still commonly known as Denver City), the seat of Arapahoe County.[3]
The Territory of Colorado renames Guadalupe County as Conejos County after only six days.[4]
November 5The Territory of Colorado votes to move the territorial capital from Denver City to Colorado City, the seat of El Paso County.
November 1The Territory of Colorado creates 17 original counties: Arapahoe, Boulder, Clear Creek, Costilla, Douglas, El Paso, Fremont, Gilpin, Guadalupe, Huerfano, Jefferson, Lake, Larimer, Park, Pueblo, Summit, and Weld County.[4]
September 9The first session of The Territory of Colorado convenes in Denver City. The legislature reworks most of the laws of the Provisional Government of the Territory of Jefferson.
June 6Jefferson Territorial Governor Robert Williamson Steele proclaims the Territory of Jefferson officially disbanded after meeting with Colorado Territorial Governor William Gilpin.
May 29Governor William Gilpin arrives in Denver City.
April 12The American Civil War begins with the Battle of Fort Sumter.
March 25U.S. President Abraham Lincoln appoints William Gilpin of Missouri to be the first Governor of the Territory of Colorado.
March 4Abraham Lincoln assumes office as the 16th President of the United States.
February 28U.S. President James Buchanan signs the An Act to provide a temporary Government for the Territory of Colorado,[24] creating the free Territory of Colorado. The new territory is created from the unorganized territory previously part of the Territory of Kansas, the northern portion of the Territory of New Mexico, the eastern portion of the Territory of Utah, and the southwestern portion of the Territory of Nebraska. The new name is chosen because the Colorado River is thought to originate somewhere in the territory. The new territory is 41% smaller than the extralegal Jefferson Territory. The boundaries of the Colorado Territory are essentially the same as the present State of Colorado.
February 8Seven secessionist slave states create the Confederate States of America.
January 29U.S. President James Buchanan signs An Act for the Admission of Kansas into the Union, creating the free State of Kansas from the eastern portion of the Territory of Kansas. The western portion of the Kansas Territory becomes unorganized territory, although the Provisional Government of the Territory of Jefferson continues to act as the de facto government.
1860November 13The Jefferson Territorial Legislature moves from Denver City to Golden City, the seat of Jefferson County.
November 6Abraham Lincoln is elected President of the United States. Seven slave states will secede from the United States of America before February 8, 1861.
August 7A proclamation by Territorial Governor Steele proposes a merger of the Jefferson Territory with the Kansas Territory. Bleeding Kansas rejects the proposal outright.
April 1The 1860 United States Census enumerates the population of the Pike's Peak Country, later determined to be 34,277. Most miners in the backcountry prospecting for gold could not be counted, so there may have been a substantial undercount.
February 1The Territory of New Mexico creates Mora County from parts of Taos County and San Miguel County. The new county extends into the southern portion of the Jefferson Territory and the future State of Colorado.[4]
January 23The second session of the Jefferson Territorial Legislature convenes in Denver City, the seat of Arrappahoe County.
January 1At the behest of the Jefferson Territorial Legislature, Samuel Beall requests that Congress approve the new Territory of Jefferson. (Congress is debating slavery and does not respond.)

1850s
YearDateEvent
1859December 3The Jefferson Territory grants a charter to the consolidated City of Denver, Auraria, and Highland, more commonly known as Denver City, as the territorial capital and seat of Arrappahoe County.
November 28The Jefferson Territory creates 12 counties: Arrappahoe, Cheyenne, El Paso, Fountain, Heele, Jackson, Jefferson, Mountain, North, Park, St. Vrain, and Saratoga County.[4]
November 7The first session of the Jefferson Territorial Legislature convenes in Denver City.
October 24Voters of the Pike's Peak Country approve the establishment of the Provisional Government of the Territory of Jefferson by a vote of 1,852 to 280 and elect Robert Williamson Steele the first (and only) Governor of the Territory of Jefferson. The boundaries of the territory are the 102nd meridian west north to the 43rd parallel north, west to the 110th meridian west, south to the 37th parallel north, and east back to the 102nd meridian west. The Territory of Jefferson includes all of the future State of Colorado, the western portion of the future State of Nebraska, the southeastern portion of the future State of Wyoming, the eastern portion of the future State of Utah, and the western two miles of the future State of Kansas.
September 24Voters of the Pike's Peak Country reject a proposal to create a Provisional State of Jefferson.
June 16Golden City is established 13 miles (21 km) west of Denver City in northwestern Kansas Territory.
May 6John H. Gregory discovers the first hard rock gold in the Rocky Mountains, a rich gold-bearing vein at Gregory Gulch, 28 miles (45 km) west of Denver City.
April 23William Byers publishes the first edition of the Rocky Mountain News, the Rocky Mountain region's first newspaper, at Denver City.
April 22The Boulder, Nebraska Territory post office opens.[25][26]
February 7The Territory of Kansas splits Arapahoe County into the six counties of Arapahoe, Broderick, El Paso, Fremont, Montana, and Oro, and creates the new Peketon County farther east and south. The counties are never organized.[4]
January 18The Platteville, Nebraska Territory post office opens.[25]
The Auraria, Kansas Territory post office opens.[26]
1858November 22William Larimer establishes the rival townsite of Denver City across Cherry Creek from Auraria.
November 1Green Russell establishes the townsite of Auraria near the Cherry Creek Diggings in Arapahoe County, Kansas Territory.[4]
SeptemberNews of gold discoveries in northwestern Kansas Territory reaches Omaha and Kansas City, precipitating the Pike's Peak Gold Rush.
AugustA party from Lawrence, Kansas Territory establishes the townsite of Montana City one mile (1.6 km) north of the Little Dry Creek Diggings in Arapahoe County, Kansas Territory.
JulyGeorgia prospectors Green Russell and Sam Bates discover a placer deposit yielding about 20 troy ounces (622 grams) of gold near the mouth of Little Dry Creek in Arapahoe County, Kansas Territory.
springAntoine Janis establishes the town of Colona on the Cache la Poudre River in western Nebraska Territory.
springThe U.S. Army builds Fort Garland in the San Luis Valley to replace Fort Massachusetts six miles to the north.
1857summerA party of Mexican-American prospectors from Taos County, New Mexico Territory dig for gold along the South Platte River below the mouth of Little Dry Creek in Arapahoe County, Kansas Territory.
1856January 5The Territory of Utah creates Beaver County from a part of Iron County which extends into the future State of Colorado.[4]
1855August 25The Territory of Kansas creates Arapahoe County in the extreme western portion of the territory in what is now Colorado. Despite several attempts, the county is never organized.[4]
1854May 30U.S. President Franklin Pierce signs An Act to Organize the Territories of Nebraska and Kansas. The Territory of Kansas includes all of the future State of Colorado east of the Continental Divide of the Americas and south of the Fortieth parallel north (the Baseline). The Territory of Nebraska includes all of the future State of Colorado east of the Continental Divide and north of the Fortieth parallel north.
1852June 22The U.S. Army establishes Fort Massachusetts in the San Luis Valley of northern New Mexico Territory, the first U.S. Army fort in the future State of Colorado.
March 3The new Territory of Utah creates ten counties, including Great Salt Lake, Green River, Iron, Sanpete, Utah, and Washington counties which extend into the future State of Colorado.[4]
January 9The new Territory of New Mexico creates nine original counties, including Taos County which extends into the future State of Colorado.[4]
1851April 9The first permanent European-American settlement in the future State of Colorado is established at San Luis de la Culebra in the northern New Mexico Territory by settlers from the Taos area.
April 5The State of Deseret dissolves and yields to the Territory of Utah.
1850September 9The Territory of New Mexico and the Territory of Utah are established as part of the Compromise of 1850. U.S. President Millard Fillmore signs An Act proposing to the State of Texas the Establishment of her Northern and Western Boundaries, the Relinquishment by the said State of all Territory claimed by her exterior to said Boundaries, and of all her Claims upon the United States, and to establish a territorial Government for New Mexico. The Territory of New Mexico includes the southeastern portion of the future State of Colorado lying south of the 38th parallel north and east of the Continental Divide of the Americas. President Fillmore also signs An Act to establish a Territorial Government for Utah. The Territory of Utah includes all of the future State of Colorado lying west of the Continental Divide of the Americas.
June 22Georgia prospector Lewis Ralston pans about a quarter of a troy ounce (8 grams) of gold near the mouth of a creek (later named Ralston Creek) in northwestern Kansas Territory, the first recorded discovery of gold in the Rocky Mountain region. Unimpressed, his party hurries on to the California goldfields.

1840s
YearDateEvent
1849August 21Proprietor William Bent destroys Bent's Fort.
March 12The Mormon settlers of the Great Salt Lake Valley create the Provisional Government of the State of Deseret and elect Brigham Young as the first (and only) Governor. The proposed state includes the entire Great Basin and the entire drainage basin of the Colorado River within the United States. Although the proposed State of Deseret includes the western portion of the future State of Colorado, it has no actual presence in the region.
March 14Ute warriors kill mountain man Bill Williams in the San Luis Valley following the Frémont expedition.
1848December 22Ignoring a warning from guide Bill Williams, John C. Frémont's private expedition for a proposed St. Louis to San Francisco railroad along the 38th parallel north becomes mired in snow of the La Garita Mountains. Ten men and 160 mules will die in the debacle.
February 2The United States and United Mexican States sign the Treaty of Guadalupe Hidalgo to end the Mexican–American War. Mexico relinquishes all of its northern territories. All land in the future State of Colorado becomes unorganized United States territory.
1847January 19U.S. civilian governor Charles Bent is killed by a band of insurgents at his home in Taos. First Secretary Donaciano Vigil assumes office as the second U.S. civilian governor of New Mexico.
1846September 25General Stephen W. Kearny and troops depart for California. Colonel Sterling Price assumes command as the second U.S. military governor of New Mexico.
September 22Brigadier General Stephen W. Kearny appoints Charles Bent as the first U.S. civilian governor of New Mexico.
August 22Brigadier General Stephen W. Kearny assumes command as the first U.S. military governor of New Mexico.
August 18Troops under the command of General Stephen W. Kearny seize Santa Fe for the United States with little resistance.
July 31Brigadier General Stephen W. Kearny stages troops at Bent's Fort for an invasion of Santa Fe de Nuevo México in the Mexican–American War.
May 13The United States declares war on the Mexican Republic.
April 25The Thornton Affair becomes the first skirmish of the Mexican–American War.
February 14The State of Texas cedes the territorial claims of the Republic of Texas to the United States. The boundaries of the State of Texas within that territory remain undefined. The United States now claims the Rio Grande as its border with Mexico.
1845December 29The United States admits the Republic of Texas to the Union as the slave State of Texas but declines to define its borders. The Mexican Republic maintains that Texas is still its territory by the Treaty of Limits of 1828 and states that it will fight to regain Texas.
1842June 10U.S. Army Lieutenant John C. Frémont, guide Kit Carson, and cartographer Charles Preuss begin a two-year survey of the High Plains. Maps created by the survey will become guides for the South Platte Trail.

1830s
YearDateEvent
1838October 6The American Fur Company closes Fort Jackson. The fort is destroyed to prevent its use by competitors.
1837springFrontier trader Ceran de Hault de Lassus de Saint Vrain establishes Fort Saint Vrain at the confluence of the South Platte River with Saint Vrain Creek.
springFrontier traders Peter A. Sarpy and Henry Fraeb establish Fort Jackson on the South Platte River for the American Fur Company.
March 6U.S. Secretary of State John Forsyth accepts the credentials of William H. Wharton as Republic of Texas Minister to the United States of America. Mexico protests the United States recognition of the Republic of Texas as a violation of the Treaty of Limits of 1828.
1836May 14Texians force captured General Santa Anna to sign the coerced Treaties of Velasco recognizing the independence of the Republic of Texas. Mexico neither acknowledges nor ratifies these treaties. Based upon these treaties, the Republic of Texas claims all land north and east of the Rio Grande del Norte to the United States border and the 45th parallel north. The Republic of Texas never occupies the region west of the 100th meridian west and this western region remains in Mexican hands. The disputed region will later become portions of the future U.S. states of New Mexico, Texas, Oklahoma, Kansas, Colorado, and Wyoming.
May 2Texians (immigrants from the United States living in the Mexican state of Coahuila y Tejas) declare the independence of the Republic of Texas from Mexico.
springFrontier trader Lancaster Lupton establishes Fort Lancaster on the South Platte River 12 miles (19 km) upstream from Saint Vrain Creek.
1835October 2The Texian Revolt begins with the Battle of Gonzales.
springFrontier traders Louis Vasquez and Andrew Sublette establish Fort Vasquez on the South Platte River.
1833springFrontier trader William Bent establishes Bent's Fort on the north bank of the Arkansas River, the United States-Mexico border. The fort serves fur traders and travelers on the Santa Fe Trail. The fort is the first American establishment in the future State of Colorado.

1820s
YearDateEvent
1828January 12The United States and Mexico sign the Treaty of Limits affirming the boundaries set by the Adams–Onís Treaty of 1819.
1821December 26Spanish Governor Facundo Melgares receives orders that Santa Fe de Nuevo México is now an intendance of the Mexican Empire. Melgares swears fealty to the empire and becomes the first Mexican Governor of Santa Fe de Nuevo México.
September 1William Becknell and a party of frontier traders leave New Franklin, Missouri bound for Santa Fe by way of the upper Arkansas and Purgatoire rivers. The Becknell route will become the Mountain Branch of the Santa Fe Trail.
August 24Ferdinand VII of Spain signs the Treaty of Córdoba recognizing the independence of the Mexican Empire. The Spanish portion of the future State of Colorado becomes part of the Mexican territory of Santa Fe de Nuevo México, although there is no permanent Mexican presence in the region.
August 10The State of Missouri is admitted to the Union. The rest of the Territory of Missouri becomes unorganized United States territory.
March 2U.S. President James Monroe signs An Act to authorize the people of the Missouri territory to form a constitution and state government, and for the admission of such state into the Union on an equal footing with the original states, and to prohibit slavery in certain territories.
February 22The Adams–Onís Treaty of 1819 takes effect. The United States relinquishes all land in the future State of Colorado south and west of the Arkansas River or the meridian 106°20'35" west. The rest of the land in the future state becomes part of the Territory of Missouri.
1820July 14Edwin James and two other members of a U.S. Army expedition led by Major Stephen Long make the first recorded ascent of Pikes Peak. Major Long names the mountain James Peak.

1810s
YearDateEvent
1819springSpanish Governor Facundo Melgares orders the construction of a military fort near Sangre de Cristo Pass to block a possible invasion of Santa Fe de Nuevo México from the United States. The fort becomes the only Spanish establishment in the future State of Colorado, only to be abandoned in 1821. The U.S. invasion of Nuevo México will not occur until 1846.
February 22The United States and the restored Kingdom of Spain sign the Adams–Onís Treaty. The United States relinquinshes its claim to land west of the 100th meridian west of Greenwich and south and west of the Arkansas River and south of the 42nd parallel north. Spain relinquishes Florida and all claims to land north of the 42nd parallel in North America.
1812June 4U.S. President James Madison signs An Act providing for the government of the territory of Missouri. The Territory of Louisiana is renamed the Territory of Missouri.
1810August 1Mexican priest Miguel Gregorio Antonio Ignacio Hidalgo-Costilla y Gallaga Mandarte Villaseñor (Hidalgo) proclaims the independence of Mexico from the Napoleonic Kingdom of Spain in the village of Dolores.
Zebulon Pike publishes The expeditions of Zebulon Montgomery Pike to Headwaters of the Mississippi River, through Louisiana Territory, and in New Spain, during the Years 1805-6-7. His journals will become a popular guide to the Upper Mississippi Basin, the Great Plains, and the Southern Rocky Mountains.

1800s
YearDateEvent
1807February 26Spanish cavalrymen arrest the U.S. Army reconnaissance expedition led by Captain Zebulon Pike in the San Luis Valley. The reconnaissance party will be taken to Santa Fe, then Chihuahua, before being expelled from Nueva España on July 1, 1807.
1806November 27Zebulon Pike abandons his attempt to climb the summit of the Mexican Mountains (Southern Rocky Mountains) now known as Pikes Peak. Pike will later write that the mountain "may be the highest on Earth". (Twenty-nine are higher in Colorado alone.)
November 15A U.S. Army reconnaissance expedition led by Captain Zebulon Pike first sights the "great summit" of the "Mexican Mountains" that will later bear his name.
1805March 3U.S. President Thomas Jefferson signs An Act further providing for the government of the district of Louisiana. The District of Louisiana is reorganized as the self-governing Territory of Louisiana. The Territory of Louisiana includes all land in the future State of Colorado in the Mississippi River watershed including the disputed area southwest of the Arkansas River.
1804October 1The District of Louisiana is organized under the jurisdiction of the Territory of Indiana.
March 26U.S. President Thomas Jefferson signs An Act erecting Louisiana into two territories, and providing for the temporary government thereof. The portion of the Louisiana Purchase north of the 33rd parallel north is designated the military District of Louisiana.
1803December 20France turns its colony of La Louisiane over to the United States. The United States and Spain disagree over the western boundary of the territory. The United States maintains that Louisiana includes the Mississippi River and its entire western drainage basin. Spain maintains that its territory includes (1) all land west of the Continental Divide of the Americas including Alta California, and (2) all land south of the Arkansas River and west of the Medina River including Santa Fe de Nuevo México, and (3) all land south of the Red River and west of the Calcasieu River including Tejas. The area in dispute includes all land in the future State of Colorado in the Mississippi River watershed southwest of the Arkansas River.
April 30The United States and the French Republic sign the Louisiana Purchase Treaty.
1800October 1Under pressure from Napoléon Bonaparte, the Kingdom of Spain transfers the colony of la Luisiana back to the French Republic with the secret Third Treaty of San Ildefonso.

1790s
YearDateEvent
1792October 3French frontiersman Pierre "Pedro" Vial arrives in Saint-Louis from the Spanish settlement of Santa Fe. The route he followed will become the Cimarron Branch of the Santa Fe Trail.

1780s
YearDateEvent
1783September 3The Treaty of Paris is signed in Paris by representatives of King George III of Great Britain and representatives of the United States of America. The treaty affirms the independence of the United States and sets the Mississippi River as its western boundary.

1770s
YearDateEvent
1778Bernardo de Miera y Pacheco, cartographer for the Dominguez–Escalante Expedition, publishes his map of the expedition across the Colorado Plateau. His map becomes the foundation of a future trade route later known as the Old Spanish Trail.
1776July 29A Spanish-Franciscan expedition led by Franciscan priests Francisco Atanasio Domínguez and Silvestre Vélez de Escalante sets out from La Villa Real de la Santa Fé de San Francisco de Asís (Santa Fe) in search of an overland route to the Presidio Reál de San Carlos de Monterey (Monterey). The expedition follows the 1765 route of Juan Rivera northwest across the Colorado Plateau. The expedition fails to reach Las Californias, but reaches the lower Paria River in the future State of Arizona before returning to Santa Fe.
July 4Representatives of the thirteen United States of America sign the Declaration of Independence from the Kingdom of Great Britain.

1760s
YearDateEvent
1765JulyGovernor Tomás Vélez Cachupin of Santa Fe de Nuevo México dispatches an expedition led by Juan Maria Antonio Rivera to explore the San Juan Mountains and the Colorado Plateau.
1762November 13Fearing the loss of its American territories in the Seven Years' War, the Kingdom of France transfers its colony of La Louisiane to the Kingdom of Spain with the secret Treaty of Fontainebleau. This ends the competition between France and Spain on the Great Plains.

1730s
YearDateEvent
1739July 5On a voyage up the Arkansas River to the confluence of the Purgatoire River (in the future State of Colorado), Pierre Antoine and Paul Mallet encounter an Arikara man who agrees to guide them to Santa Fe. This is the first contact between France and Spain in the Rocky Mountain region.

1690s
YearDateEvent
1692September 14Diego de Vargas Zapata y Luján Ponce de León y Contreras completes the reconquest of the Spanish colony of Santa Fe de Nuevo Méjico to end the Pueblo Revolt.

1680s
YearDateEvent
1682April 9René-Robert Cavelier, Sieur de La Salle, claims the Mississippi River and its watershed for the Kingdom of France and names the region La Louisiane in honor of King Louis XIV. The Mississippi Basin is later determined to be the fourth most extensive on Earth and includes lands inhabited by hundreds of thousands of native peoples and lands previously claimed by Spain, France, and England. The Louisiane claim includes all land in the future State of Colorado east of the Continental Divide of the Americas and the Sangre de Cristo Mountains. This will set up a rivalry among native peoples, France, Spain, and eventually the United States in the area.
1680August 13Tewa shaman Popé of Ohkay Owingeh leads the Pueblo Revolt against the Spanish rulers of Santa Fe de Nuevo Méjico. The Spanish settlers flee down the Rio Grande to El Paso del Norte.

1590s
YearDateEvent
1598July 12Don Juan de Oñate Salazar establishes the New Spain colony of Santa Fe de Nuevo Méjico at the village of San Juan de los Caballeros adjacent to the Ohkay Owingeh Pueblo at the confluence of the Río Bravo (Rio Grande) and the Río Chama. The colony will eventually encompass most of the future U.S. states of New Mexico and Colorado and portions of Kansas, Oklahoma, Texas, Arizona, and Utah.

1540s
YearDateEvent
1541June 28A Spanish military expedition led by Hernando de Soto, Governor of Cuba, become the first Europeans to cross the Mississippi River.
springThe Spanish military expedition led by Francisco Vásquez de Coronado leaves the Tiwa pueblos and searches the Great Plains for Quivira. The expedition may, or may not, have crossed the southeast corner of the present U.S. State of Colorado.
winter The Tiwa resist the occupation by the Coronado expedition but hundreds are killed in the Tiguex War.
1540autumn The military expedition lead by Francisco Vásquez de Coronado, reaches the Tiwa pueblos along the Río Bravo (Rio Grande). The expedition occupies several of the pueblos.
July 7The military expedition lead by Francisco Vásquez de Coronado, reaches the Zuni pueblo of Hawikuh. The Zuni resist but are driven off by the Spanish soldiers.
February 23Francisco Vásquez de Coronado, Governor of Nueva Galicia, departs Compostela, México commanding a Spanish military expedition of 400 soldiers and 1,300 to 2,000 Mexican Indian allies in search of the Seven Cities of Cibola.

1510s
YearDateEvent
1519autumn A Spanish naval expedition along the northeastern coast of Mexico charts the mouths of several rivers including the Río de Nuestra Señora (Rio Grande).
1513September 29Spanish conquistador Vasco Núñez de Balboa crosses the Isthmus of Panama and arrives on the shore of a sea that he names Mar del Sur (the South Sea, later named the Pacific Ocean). He claims the sea and all adjacent lands for the Queen of Castile. This includes the portion of the future State of Colorado west of the Continental Divide of the Americas.

1490s
YearDateEvent
1493May 5Pope Alexander VI (born Roderic de Borja in Valencia) issues the papal bull Inter caetera which splits the non-Christian world into two halves. The eastern half goes to the King of Portugal for his exploration, conquest, conversion, and exploitation. The western half (including all of North America) goes to the Queen of Castile and the King of Aragon for their exploration, conquest, conversion, and exploitation. The indigenous peoples of the Americas have no idea that any of these people exist.
1492October 12Genoese seaman Cristòffa Cómbo (Christopher Columbus) leading an expedition for Queen Isabella I of Castile lands on the Lucayan island of Guanahani that he renames San Salvador. This begins the Spanish conquest of the Americas.

Before 1492
EraEvent
1300–1525 CEJicarilla Apache migrate to the southern extent of the Rocky Mountains from Alaska and Northwestern Canada.
1276–1299 CEA prolonged drought on the Colorado Plateau forces many Ancestral Puebloans to migrate southeast into the Rio Grande Valley.
c. 1150 CEThe Slumgullion Earthflow dams the Lake Fork to form Lake San Cristobal, presently the second largest natural lake in Colorado.
c. 1100 CEAncestral Puebloans begin construction of cliff houses on Mesa Verde.
c. 550 CEAncestral Puebloans move onto Mesa Verde.
c. 4900 BCEPaleoamericans camp at the Magic Mountain Site near Golden.
c. 8670 BCEPaleoamericans of the Folsom culture camp at the Lindenmeier Site in present-day Larimer County.
c. 12,000 BCEDuring a centuries long period of warming, ice-age Paleoamericans from Beringia begin using the ice-free corridor east of the Rocky Mountains to migrate throughout the Americas.


 2000s   1900s   1800s   Statehood   Territory   1700s   1600s   1500s   Before 1492 

See also

References

References are included in the linked articles.

  1. "Antiquities Act". National Park Service. November 16, 2020. Retrieved November 16, 2020.
  2. "Park Anniversaries". National Park Service. October 30, 2020. Retrieved November 16, 2020.
  3. "List of Incorporated Cities and Towns in Colorado" (PDF). Colorado State Archives. Retrieved November 18, 2020.
  4. "Colorado: Individual County Chronologies". Newberry Library. 2009. Retrieved November 17, 2020.
  5. https://www.bizjournals.com/denver/stories/2000/12/25/story7.html
  6. "Establishment and Modification of National Forest Boundaries and National Grasslands" (PDF). United States Forest Service. 2012. Retrieved November 16, 2020.
  7. Del Papa, Dr. E. Michael; Warner, Mary P (October 1987). A Historical Chronology of the Electronic Systems Division 1947-1986 (PDF) (Report). Retrieved 2012-07-19.
  8. http://www.astronautix.com/fam/titan.htm Archived 2010-09-14 at the Wayback Machine
  9. Sixty-eighth United States Congress (June 2, 1924). "An Act To authorize the Secretary of the Interior to issue certificates of citizenship to Indians" (PDF). Retrieved November 16, 2020.
  10. Garrett, John W. (December 5, 1908). "Colorado Springs Celebrates". Sporting Life. 52 (13): 1. Colorado Springs, Col., November 27--The Thanksgiving matinee shoot, held on the Broadmoor Shooting Grounds by the Colorado Springs Gun Club was a most pleasant, social shoot, the only detraction being the quite disagreeable chilly weather so rarely experienced here thus early in the Fall. …luncheon at the Alamo Hotel. … In the Spalding medal…Joe H. Rohrer…winning with 94. … John W. Garrett, who had held the medal since 1902…
  11. Sixty-fourth United States Congress (August 25, 1916). "An Act To establish a National Park Service, and for other purposes" (PDF). Retrieved November 16, 2020.
  12. Fifty-ninth United States Congress (June 8, 1906). "An Act For the preservation of American antiquities" (PDF). Retrieved November 16, 2020.
  13. Fifty-first United States Congress (March 3, 1891). "An act to repeal timber-culture laws, and for other purposes" (PDF). Retrieved November 16, 2020.
  14. "Ft. Logan to be Convalescent Center Starting at Midnight". The Denver Post. April 14, 1944. Retrieved July 19, 2012.
  15. "Archived copy". Archived from the original on 2007-12-15. Retrieved 2007-12-11.CS1 maint: archived copy as title (link)
  16. "History and Timeline | Friends of Historic Fort Logan".
  17. Stover, C. W.; Coffman, J. L. (1993), Seismicity of the United States, 1568–1989 (Revised) – U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, p. 188
  18. Ulysses S. Grant (August 1, 1876). "Proclamation 230—Admission of Colorado into the Union". The American Presidency Project. Retrieved November 16, 2020.
  19. Colorado Constitutional Convention (March 14, 1876). "Proceedings of the Constitutional Convention" (PDF). Retrieved November 16, 2020.
  20. Colorado Constitutional Convention (March 14, 1876). "Constitution of the State of Colorado" (PDF). Retrieved November 16, 2020.
  21. Forty-third United States Congress (March 3, 1875). "An act to enable the people of Colorado to form a constitution and State government, and for the admission of the said State into the Union on an equal footing with the original States" (PDF). Retrieved November 16, 2020.
  22. ), Geological Survey (U.S (1902). "Bulletin - United States Geological Survey".CS1 maint: numeric names: authors list (link)
  23. "Shovels and Plumb Bobs".
  24. Thirty-sixth United States Congress (February 28, 1861). "An Act To provide a temporary Government for the Territory of Colorado" (PDF). Retrieved November 16, 2020.
  25. "COLORADO Post Offices". United States Postal Service. 2020. Retrieved November 20, 2020.
  26. Mayer, Frederick. "Putting Together Colorado Territory Philatelically" (PDF). Richard Frajola. Retrieved November 20, 2020.

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