Penn Line

Electric MARC HHP-8 at Odenton station.

The Penn Line uses diesel as well as electric locomotives for powering trains. Most electric and rush hour diesel trains are 6-8 cars long, and are primarily made up of Kawasaki bi-levels. During the day, shorter 4-6 car MultiLevels or single level diesel trains from the Brunswick and Camden lines are used on the Penn Line. For the spring and summer months, weekend Penn Line trains also include a single-level Bike Car that is specially equipped to accommodate bicyclists.[5]

All trains are operated in push-pull configuration with the cab-car end towards Washington.

All of the stations from Washington Union Station up to Halethorpe have high-level platforms, and all of the subsequent stations from West Baltimore up to Perryville, with the exception of Penn Station, have low-level platforms. This precludes the use of MARC's ex-Metra low-level boarding gallery railroad cars on the Penn Line.

MARC runs 58 Penn Line trains during a normal weekday. A majority of these trains (39 each day) originate/terminate between Union Station in Washington and Penn Station in Baltimore. An additional 11 trains originate/terminate between Union Station and Perryville, MD, and another 5 originate/terminate between Union Station and Martin State Airport. A single morning train and a single evening train run between Perryville and Penn Station, and a single early morning train runs from Martin State Airport to Penn Station.[6] Unlike MARC's other two lines, the Penn Line operates all throughout the day and well into the night.

On December 7, 2013, the Penn Line also began offering limited weekend service.[7] Penn Line weekend service consists of 9 round trips on Saturday and 6 round trips on Sunday—primarily between Penn Station and Union Station. Several trains extend service to Martin State Airport, and all trains skip Seabrook.[5]

Beginning on December 13, 2014, a separate Bike Car was added to some weekend Penn Line trains.[8] Bike Cars are reconditioned Sumitomo/Nippon Sharyo MARC IIA single-level commuter railcars. One side of each car's interior is lined with bicycle racks which are arranged to secure 23 full-sized, non-collapsible bicycles, and the other side provides seating for 40 passengers.[9] The Bike Car program was expanded during 2015 to include all weekend trains.[9] There is no extra charge for using the Bike Car, which is available on a first-come, first-served basis. Beginning in 2016, MARC began installing bike racks on its bi-level train cars and some of its single-level cars. Weekday service was intended to begin in summer 2018, however, this was delayed several times. Eventually, 35 Penn Line railcars had full-sized bicycle racks installed, and weekday use of the bike racks on the MARC Penn line officially began on January 21, 2019.[10] These railcars are available on most weekday rush-hour Penn Line trains and on all weekend trains. As with the former Bike Cars, these services are first-come, first served with no additional charge, and the bicyclist must make sure to be able to access the platform of the station they desire.

Amtrak's Acela Express, Northeast Regional, and long distance trains share tracks along the whole of the Penn Line. Washington Union and Baltimore Penn are the second and eighth busiest Amtrak stations in the country, respectively. Amtrak connections are also available at Aberdeen, BWI Airport and New Carrollton. MARC passengers with monthly and weekly tickets can ride select Amtrak Northeast Regional trains during the week only, as part of their cross-honoring agreement.[6] Connections are also available to the Washington Metro's Orange Line at New Carrollton, Red Line at Washington Union Station, and to the MTA Light Rail at Baltimore Penn Station.[6]

The MTA has plans to extend the Penn Line to Newark station in Delaware to connect with the Wilmington/Newark Line of SEPTA or even further north to 30th Street Station in Philadelphia. The PRR's commuter route had run as far north as Philadelphia until the early 1960s.

The MTA funds a local bus connection between Newark and Baltimore with a transfer at Elkton station.[11] A bill in Maryland awaiting the signature of Governor Larry Hogan would extend MARC service from Perryville to Newark. In 2020, Representative Edward Osienski and Senator Stephanie Hansen cosponsored a resolution to the Delaware General Assembly that will add commuter rail service between Newark and Perryville, involving an extension of MARC service to connect with SEPTA at Newark and provide an alternate to Amtrak for Delaware residents wanting to travel to Baltimore and Washington, D.C. This resolution will be introduced into the Delaware General Assembly in 2021.[12]

Longer-term plans include construction of new track and extending the line past Washington Union Station to L'Enfant Plaza station and into northern Virginia.[11] The planned Purple Line that will connect all three MARC lines will connect with the Penn Line at New Carrollton.

The following stations are served by Penn Line trains; not all trains stop at all stations.

State	Town/City	Station	Connections
DC	Washington	Union Station	Amtrak: Acela Express, Capitol Limited, Cardinal, Carolinian, Crescent, Northeast Regional, Palmetto, Silver Meteor, Silver Star, Vermonter, Thruway Motorcoach to Charlottesville, Virginia MARC: Brunswick Line, Camden Line Metrorail: Red Line Metrobus, Loudoun, OmniRide VRE: Manassas Line, Fredericksburg Line MTA Commuter Bus: 915, 929
MD	New Carrollton	New Carrollton	Amtrak: Northeast Regional, Vermonter Metrorail: Orange Line Metrobus: 87, B21, B22, B24, B27, B29, C28, F4, F6, F12, F13, F14, G12, G14, T14, T18 Prince George's "TheBus": 15X, 16, 21, 21X
	Seabrook	Seabrook
	Bowie	Bowie State	Bowie State University
	Odenton	Odenton	Anne Arundel County 202 Bus
	Linthicum Heights	BWI Airport	Amtrak: Acela Express, Northeast Regional, Vermonter Baltimore Light RailLink via BWI Marshall Airport Shuttle (see BWI Marshall Airport station) BWI Airport via BWI Marshall Airport Shuttle MTA Maryland: 17, 99, 201 Howard Transit Silver
	Halethorpe	Halethorpe	MTA Maryland: 77 University of Maryland, Baltimore County Halethorpe Line
	Baltimore	West Baltimore	MTA Maryland: 23, 40, 47, 51 (1 block east)
		Penn Station	Amtrak: Acela Express, Cardinal, Carolinian, Crescent, Northeast Regional, Palmetto, Silver Meteor, Silver Star, Vermonter MTA Maryland: 3, 11, 61, 64 Baltimore Light RailLink: Penn/Camden Shuttle Charm City Circulator: Purple Route
	Middle River	Martin State Airport	Martin State Airport MTA Maryland: 24, 160
	Edgewood	Edgewood
	Aberdeen	Aberdeen	Amtrak: Northeast Regional Harford Transit: 1, 1A, 4, 6, and 6A
	Perryville	Perryville	Cecil Transit: 2, 5

• MTA MARC Train