U.S. Route 36 in Colorado

Sign on US 34 approaching the western endpoint of US 36 at Deer Ridge Junction in Rocky Mountain National Park.

U.S. Highway 36 begins at Deer Ridge Junction in Rocky Mountain National Park, where it intersects U.S. Highway 34 (Trail Ridge Road) on the eastern slope of the Rocky Mountains. It exits the park at the Beaver Meadows Visitor Center and enters the town of Estes Park, where it is briefly overlapped with Business US 34 until it meets (but does not cross) the main US 34 again at an intersection shaped like the letter K. On its way out of Estes Park it intersects SH 7 at South St. Vrain Avenue, for the first of three times.

It then descends southeast through North St. Vrain Canyon to the town of Lyons, which it enters on Main Street. At 5th Avenue in Lyons, it intersects SH 7 again, beginning an overlap to Boulder which is signed only as US 36. At 5th Avenue and Main Street in Lyons, it divides into a pair of one-way streets with the eastbound direction traveling one block south on 5th Avenue and turning east onto Broadway Street, and the westbound direction using Main Street. The two directions reunite in two blocks and leave Lyons southeastward as four-lane Ute Highway. Just outside Lyons, US 36 turns south at a signalized intersection onto two-lane North Foothills Highway, while SH 66 continues east to Longmont. From Lyons to Boulder, US 36 pretty much traces the edge of the foothills.

US 36 enters Boulder on four-lane-wide 28th Street, where it serves the city's main shopping area. On the north side of Boulder, it intersects SH 119 at Diagonal Highway, beginning a 1.4 mile overlap that extends until SH 119 turns west onto Canyon Boulevard towards Nederland. One block farther south, SH 7 diverges from its overlap with US 36 by turning east onto Arapahoe Avenue. Leaving the Boulder shopping district, US 36 crosses Boulder Creek and passes through the University of Colorado campus area as an expressway to the interchange with Baseline Road, where it meets Spur US 36, a two-block long connector along 27th Way to SH 93, signed only as "To SH 93" and "To US 36".

Just after the Baseline Road interchange, US 36 changes to a southeasterly direction, using the route of the original Denver-Boulder Turnpike, a toll road from its opening in 1952 until 1967.[2][3] The road intersects SH 157 Foothills Parkway on its way out of Boulder. Northwestbound traffic approaching Boulder on the turnpike can stop at the Davidson Mesa Overlook, providing a panoramic view of the Front Range mountains, the City of Boulder, and its famous Flatirons rock formation; a monument to the Denver-Boulder Turnpike's original builders is also located here.[4] Continuing southeast, the road enters the fast-growing Denver suburbs of Broomfield and Westminster, which have become popular locations for High-Tech businesses, which can be seen lining the turnpike. An interchange at 96th Street provides access to the Northwest Parkway and thereby to the E 470 outer beltway around Denver. At an interchange with SH 121 and SH 128 in Broomfield, it meets (but does not cross) U.S. Highway 287. It then has another interchange with US 287 again at Federal Boulevard near 76th Avenue in Westminster. The interchange at 76th and Federal was the terminus of the original Denver-Boulder Turnpike when it was still a toll road, but in common parlance the Turnpike now extends all the way east to I-25.

The US 36 bikeway, part of the multi-modal Fastracks US 36 Express Lanes Project, mostly parallels the road between Table Mesa Drive in Boulder and 80th Avenue in Westminster, the first 11-mile stretch between Westminster and Louisville/Superior opening on Bike-to-Work Day in June 2015,[5] the full route to Table Mesa in Boulder in March 2016.[6][7]

At the very complicated junction of US 36, I-25, I-76, and I-270, US 36 emerges overlapped and unsigned with I-270, and continues overlapped and unsigned with I-70 when I-270 ends near the former Stapleton Airport site. At Colfax Avenue, this I-70/US 36 overlap is also joined by US 287 (the third time the two highways come into proximity) and US 40. From the interchange with Colfax Avenue, the road continues to Watkins and then to Byers, unsigned in its four-way overlap with I-70, US 40, and US 287.

At Byers, US 36 heads eastward on its own as a separate rural highway, while the I-70/US 40/US 287 overlap curves to the southeast. US 36 passes through several very small settlements including Last Chance, Lindon, Anton, and Cope in Washington County and Joes and Idalia in Yuma County. Many of the towns on this desolate 105-mile (169 km) section of highway are so small they do not provide basic traveler services such as gasoline, and winter drivers are cautioned by signs that there is no snowplowing at night. At Cope, it is joined by SH 59 for about 6 miles (9.7 km). In Yuma County, near Idalia, it jogs north, becoming concurrent with US 385 for about 3 miles (4.8 km) before turning east again and continuing about 10 miles (16 km) to the Kansas border.[1]

The Denver-Boulder Turnpike was championed by business and university interests in Boulder due to there being no direct route between Denver and Boulder.[8] The 17.3-mile (27.8 km) toll road stretched from Federal Boulevard (US 287) in Westminster to Baseline Road in Boulder, and opened on January 19, 1952 with a toll of $0.25. The Valley Highway from downtown Denver opened in 1952–1954, feeding directly into the Turnpike. Most of the new highway carried SH 185 (US 87), but traffic continuing north on that route initially had to exit at 70th Avenue, now SH 224, with the remainder of the route to Federal Boulevard becoming a realignment of SH 382. When the bonds for the Turnpike were paid off ahead of time in 1967, tolls were removed.[9]

Beginning in July 2012, the Colorado Department of Transportation built a high-occupancy toll lane (HOT lane) in each direction between Federal Boulevard and 88th Street in Louisville, Colorado.[10] Phase 1 of the project, costing $497 million, will open in summer 2015. High-occupancy vehicles and buses like RTD's Flatiron Flyer travel free in the HOT lanes, while single-occupancy vehicles must pay between $1.25 to $7.60, depending on time of day, or up to $13.68 without an electronic toll collection pass.[11] To accommodate the lanes, several bridges were replaced and shoulders were widened along the highway. Phase 2 of the project, anticipated to be complete by early 2016, will extend the HOT lanes from 88th Street to Table Mesa Drive in Boulder, Colorado, through a public–private partnership.[12]

Mileposts are based on US 36 mileage.

County	Location	mi	km	Destinations	Notes
Adams	Aurora	76.394	122.944	I-70 (US 36 / US 40 / US 287)	Western terminus; I-70 exit 292
	Watkins	79.730	128.313	Watkins Road (I-70 BS south) to I-70	Northern terminus of I-70 Bus.
	Bennett	88.836	142.968	SH 79 south (1st Street) to I-70	Western end of SH 79 concurrency
		89.210	143.570	SH 79 north (Adams Street) – Prospect Valley	Eastern end of SH 79 concurrency
Adams–Arapahoe county line		91.188	146.753	I-70 – Denver	No access to I-70 east; I-70 exit 306
Arapahoe	Strasburg	95.000	152.888	To I-70 / Wagner Street
	Byers	100.937	162.442	SH 40 east	Former US 40 east
		100.998	162.541	I-70 (US 40 / US 287) / US 36	Eastern terminus; I-70 exit 316; highway continues as US 36 east.
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access