Quick Facts

NameMARC No. 7100
Manufacture Date1951
Railroad Of RecordB&O Railroad, MDOT, MARC, MTA
ManufacturerGeneral Motors, Electro-Motive Division


Built by GM-EMD in 1951 and sold to the B&O Railroad that same year, the No. 7100 began its life as a model F7-A diesel locomotive. First numbered as the B&O No. 293A and later renumbered as the No. 4553, the locomotive spent the first 24 years of its career pulling commuter passenger trains across the vast B&O network.

In the 1950s, the B&O began to reduce its unprofitable local passenger services. The railroad’s financial struggles came to a head in 1975, when the Maryland Department of Transportation took over the operating costs of the B&O’s commuter services. With its passenger services in decline, the B&O sold the No. 4553 to the Morrison-Knudson Company of Boise, Idaho. The locomotive would remain idle in Boise for 5 years.

In 1980, the No. 4553 was acquired by MDOT and brought into the Boise locomotive shops for extensive renovations. The 1,500 horsepower, 16-cylinder 567B diesel engine was replaced with a “head-end power plant” – or “HEP” – comprised of a Cummins diesel engine coupled to an A/C generator. Modernized lighting, heating, and air conditioning systems were connected to the HEP. The No. 4553 was no longer considered a “real” locomotive, but rather an Auxiliary Power Control Unit, or “APCU.” This means that the unit can control a train from the back end, but it lacks the power required to pull a train on its own.

When the new APCU was delivered to MDOT in 1981, it bore a new number, No. 7100, and it wore the silver and orange colors of the MDOT fleet. Between 1983 and 1984, the state of Maryland created MDOT, forming the Maryland Area Regional Commuter service, also known as “MARC.” The Maryland Transit Administration, or “MTA,” then began MARC’s operations in 1992, but MARC continued to operate under its own name. The No. 7100 serviced the MARC commuter lines until the late 1990s.

Virtual Tour:

Visual Tour Description:


The MARC 7100 is a silver toned locomotive with orange and royal blue detailing. On each side there is one horizontal blue stripe, one horizontal orange stripe, orange safety rails, and an all-capitalized MARC in the center. The front of the locomotive is rounded with the same MARC written, a 7100 plaque on either side, orange safety rails, and a circular blue light at the center. The rear side has a continuation of the blue and orange stripes from both sides, orange safety rails, circular red safety lights, and a door. The underside of the locomotive is the same royal blue as the detailing.


The interior of the MARC 7100 has a similar grey tone to the exterior on the walls, flooring, and ceiling. The rear of the locomotive features multiple control panels along the back wall and sides. Multiple bright red panels read DANGER. The large HEP unit sits in towards the center of the rear section, making the space rather tight. The front of the interior features two seats with a control box in between. A small window on each side sits level with the chairs, the windshield is in two sections.


Monthly Tours

Go inside the No. 7701 “Dreamland Sleeper”

August 14, 17 & 18

Climb aboard the Pere Marquette No. 11 Diesel Switcher

September 11, 14 & 15

Purchase a B&O Membership

for the ultimate ticket to explore every hidden gem in the series!

Did You Know?

The first passenger train ticket in the United States was sold on our historic site in 1830.

Knoxville, TN

We did the train ride and our guide on board was excellent (history/information for the parents).

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