This June, we are unlocking the MARC No. 7100!
The MARC No. 7100 is unlike any other locomotive in the National Museum of Railroad History & Innovation collection. 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. In 1980, the locomotive’s 1,5000 horsepower diesel engine was replaced with a “head-end power plant.” The No. 7100 was no longer considered a “real” locomotive, but rather an Auxiliary Power Control Unit (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.
The No. 7100 serviced the MARC commuter lines until the late 1990s. Today, the APCU is a symbol of technological development and modern commuter rail travel. Don’t miss your chance to step inside the cab and experience the modern railroad from an engineer’s perspective!
Tours:
Tours will be available between 10 AM – 4 PM.
Please note: This tour requires participants to climb stairs and walk on uneven pathways. For a completely physically accessible experience please see our virtual tour. Docent Tour Guides stationed near the locomotive can answer any additional questions about the history and physical description of the locomotive. Small children must be accompanied by an adult guardian at all times.
Admission:
Included with Museum Admission. FREE for Museum Members.
America 250: Unlocked
Celebrate America’s Story—One Railcar at a Time
The National Museum of Railroad History & Innovation’s annual Unlocked series returns—this year with a special tribute to America’s 250th anniversary. Each month, step inside a different piece of rail history and experience the stories that helped build a nation. In honor of this milestone, American Freedom Train No. 1 will be opened twice in 2026—January and July—offering a rare chance to celebrate the spirit of freedom and innovation that defines America’s rail legacy.
You’ll also have the opportunity to step inside the newly restored B&O No. 3316 “Washington” Observation Tavern Car.
Become a Museum Member and receive free admission for each collection piece. Don’t miss this opportunity to unlock the doors on these historic pieces!
Step inside the complete 2026 series!
American Freedom Train (AFT) No. 1
January 24, 25, & 28
The AFT No. 1 toured the United States with the 1975-1976 American Freedom Train in celebration of the United States Bicentennial.
B&O No. 3316 Pullman “Washington” Observation Tavern Car
February 25, 28 & March 1
Used on the Capitol Limited and other premier B&O passenger trains in the mid-20th century, the No. 3316 “Washington” observation tavern car represented the pinnacle of luxury rail.
B&O No. 600 John C. Davis
March 18, 21 & 22
Produced by B&O Master of Machinery in 1875, the No. 600 was the first “Mogul” type railroad intended for passenger services, and the largest locomotive in the world at the time.
B&O No. CE-10 Electric Switcher
April 15, 18 & 19
The B&O No. CE-10 once traversed the sharp turns and narrow street of Fells Point. Put into service at the dawn of the 20th century, the fully-electric locomotive was a revolution in green technology.
B&O No. 21 Passenger Coach
May 20, 23 & 24
Built by the Wason Manufacturing Company in 1868, the B&O No. 21 resembles the daytime passenger coach used by civilians and military personnel during the Civil War.
MARC No. 7100
June 17, 20 & 21
Built by GM-EMD in 1951, the MARC No. 7100’s diesel engine was replaced with a “head-end-power plant” in 1980. Now operating as an Auxiliary Power Control Unit (APCU), the No. 7100 is used solely for powering a train’s electrical systems.
American Freedom Train (AFT) No. 1
July 4, 15, 18 & 19
The AFT No. 1 will be unlocked again in honor of the nation’s 250th Independence Day, and to celebrate the 50th anniversary of the 1975-1976 American Freedom Train.
C&O No. 490 Hudson
August 19, 22 & 23
Built by ALCO in 1926, the C&O No. 490 was one of the last passenger locomotives to operate on the Chesapeake & Ohio Railway. Nicknamed the “Yellowbelly,” this “Hudson” type locomotive is recognized for its stylish streamlined body.
B&O No. 445 “Royal Blue Coach”
September 16, 19 & 20
Built by the Pullman Company c.1890, the B&O No. 445 passenger coach was rebuilt in 1927 to represent a car from the B&O’s flagship Royal Blue passenger train.
B&O No. 3528
October 21, 24 & 25
Built in 1923 and retired in 1983, the B&O No. 3528 heavyweight coach was the last commercial passenger car to service former-B&O lines.
B&O No. 147 “Thatcher Perkins”
November 20, 21 & 22
Designed to traverse the steep Allegheny Mountains and unveiled in 1863, the B&O No. 147 “Thatcher Perkins” began its career pulling military trains for the Union Army.
Purchase a Museum Membership
For the ultimate ticket to explore every hidden gem in the series!
Learn MoreMore about the B&O Unlocked Series
America 250: Unlocked
Celebrate America’s Story—One Railcar at a Time
The National Museum of Railroad History & Innovation’s annual Unlocked series returns—this year with a special tribute to America’s 250th anniversary. Each month, step inside a different piece of rail history and experience the stories that helped build a nation. In honor of this milestone, American Freedom Train No. 1 will be opened twice in 2026—January and July—offering a rare chance to celebrate the spirit of freedom and innovation that defines America’s rail legacy.
You’ll also have the opportunity to step inside the newly restored B&O No. 3316 “Washington” Observation Tavern Car.
Become a B&O Member and receive free admission for each collection piece. Don’t miss this opportunity to unlock the doors on these historic pieces!
Step inside the complete 2025 series!
B&O No. CE-15 Tunnel Clearance Car
January 15, 18 & 19
The CE-15 is believed to be the world’s only surviving tunnel clearance car and serves as a testament to a pivotal moment in locomotive design.
B&O No. CE-10 Electric Switcher
February 19, 22 & 23
The B&O No. CE-10 worked on the small rail network of Fells Point to keep Baltimore industry moving.
GC&E No. 1 “Shay”
March 19, 22 & 23
The GC&E No. 1 “Shay” is an asymmetrical engine designed to navigate the uneven tracks and sharp curves of logging country.
B&O No. X-4055 Camp Car
April 16, 19 & 20
The B&O No. X-4055, also known as the B&O No. 4723 and nicknamed “Thendara,” was originally constructed as a sleeper car and later refashioned to serve as a Maintenance-of-Way (MOW) camp car in the 1960s.
B&O No. C-2943 Caboose
May 21, 24 & 25
The B&O No. C-2943 is an example of an I-7A caboose, which is known for its steel body and protruding bay windows.
B&O No. 3684
June 18, 21 & 22
The B&O No. 3684 was the first locomotive to arrive to the B&O Railroad from a purchase of 16 GP-40 diesel-electric engines.
WM 195 Switcher
July 16, 19 & 20
The WM No. 195 is a multi-purpose engine made to travel as fast as a mainline locomotive and was used for over two decades to pull heavy coal trains.
B&O No. B-29 Jordan Spreader
August 20, 23 & 24
The B&O No. B-29 is a “Jordan Spreader,” a type of maintenance car that is considered by some to be the earliest type of railroad maintenance equipment.
B&O No. 633 Switcher
September 17, 20 & 21
The B&O No. 633 is a diesel switcher of the SW-900 model that still occasionally operates at the museum.
B&O No. 3302 “Edward G. Hooper” Observation Lounge
October 15, 18 & 19
The B&O No. 3302 “Edward G. Hooper” Observation Lounge, serves as a reminder of luxury passenger service and traveled with the Royal Blue and the Ambassador.
B&O No. C-1775 Bobber Caboose
November 20, 22 & 23
A staple of railroad imagery, “bobbers” served as business offices, mobile lookout towers, and sleeping quarters.
Purchase a B&O Membership
For the ultimate ticket to explore every hidden gem in the series!
Learn MoreUpcoming Events at the Museum
WITH GENEROUS SUPPORT FROM:
“My family had a wonderful time in this museum! It’s the perfect balance of visually appealing and interactive for my boys (ages 5 & 8). We would definitely go again!”
Celeste C.
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