Baltimore & Ohio Boxcab Diesel #50: EMC's 1800 HP Locomotive

Published: June 28, 2026

In the depths of the Great Depression, American railroads faced immense pressure to modernize. Steam locomotives dominated, but they were dirty, maintenance-intensive, and increasingly restricted in urban areas due to smoke ordinances. The Baltimore & Ohio Railroad (B&O), America’s first common carrier railroad chartered in 1827, sought innovative solutions. In 1935, it acquired a groundbreaking machine: the Electro-Motive Corporation (EMC) 1800-hp B-B boxcab diesel-electric locomotive numbered #50.

This locomotive represented one of the earliest successful experiments in mainline diesel power for passenger service. It was not merely a switcher but a full road unit capable of hauling named trains over long distances. Its story spans pioneering technology, service on iconic trains like the Royal Blue and Abraham Lincoln, corporate mergers, and eventual preservation as a museum artifact. Today, it stands as a tangible link to the dawn of the diesel era in North American railroading.

Baltimore & Ohio boxcab #50 on display at EMD's McCook, Illinois plant on September 9, 1972 during the company's celebration of fifty years of locomotive production. Paul Schumann photo.

The Dawn of Diesel Experimentation at EMC

Electro-Motive Corporation, originally a designer and marketer rather than a full manufacturer in the early 1930s, collaborated with General Electric (GE) and others to develop diesel-electric technology. By 1935, EMC had advanced beyond early switchers (like the 1925 Alco-GE-Ingersoll-Rand 60-ton units) to create experimental road locomotives.

The EMC 1800 hp B-B design emerged as a proof-of-concept. EMC subcontracted carbodies: most to GE’s Erie, Pennsylvania plant, with others built by St. Louis Car Company.

Five units were produced in August 1935:

EMC demonstrators #511 and #512
B&O #50 (serial 532)
Atchison, Topeka & Santa Fe (AT&SF) #1A and #1B

These featured a distinctive boxcab body style—rectangular, utilitarian, and functional—with control cabs at both ends, a relatively rare feature. This allowed bidirectional operation without turning the locomotive. Power came from two Winton 201-A V12 diesel engines, each rated at 900 hp, for a total of 1,800 hp. The diesel-electric transmission used generators and traction motors on the B-B trucks (two two-axle powered trucks).

The twin-engine setup provided redundancy and “headroom” for reliability, as early diesel engines were less mature than steam technology. These units pioneered multiple-unit (MU) control systems, enabling locomotives to be coupled and operated by a single crew—an innovation that shaped future designs like the EMC/EMD E-units.

B&O #50 was built specifically as a testbed/purchase unit for the railroad. Funding assistance came via a Public Works Administration (PWA) loan in 1934, which also supported streamlined passenger cars and the rebuilding of a steam locomotive. This New Deal support helped B&O modernize during economic hardship.

Entry into Service: The Royal Blue Era (1935–1937)

B&O #50 entered revenue service in August 1935 on the prestigious Royal Blue, the railroad’s flagship New York–Washington, D.C. passenger train. It replaced steam power, including the famous streamlined Pacific Lord Baltimore. This marked one of the first instances of a diesel-electric locomotive hauling a long-distance named passenger train in regular service in the United States.

Contemporary accounts described the boxcab as a “strange, 66-foot long, boxlike locomotive.” Its smooth, quiet operation and lack of smoke impressed passengers and crews alike. The unit demonstrated diesel reliability on the busy Northeast Corridor route. B&O positioned #50 as a symbol of progress, aligning with the railroad’s long history of innovation (it had operated the first steam locomotive in the U.S. for common carrier service decades earlier).

The experiment proved successful enough that B&O soon ordered streamlined EMC EA/EB units (#51 and others) in 1937 to fully dieselize the Royal Blue and other trains. #50 had served its pioneering role and was reassigned.

Transfer to the Chicago & Alton and the Abraham Lincoln

In April 1936, B&O transferred #50 to its subsidiary, the Chicago & Alton Railroad (later fully integrated). To better suit passenger aesthetics, the railroad added a semi-streamlined “shovel nose” to one end, giving it a more modern profile while retaining the boxcab body.

On the Alton, #50 hauled the Abraham Lincoln, a streamlined Chicago–St. Louis passenger train. This service highlighted the locomotive’s versatility across different routes and terrains in the Midwest. The dual-cab design proved advantageous for frequent terminal operations.

GM&O Era and Post-War Service (1940s–1950s)

When the Alton Railroad was merged into the Gulf, Mobile & Ohio Railroad (GM&O) in 1947, #50 became GM&O #1200. The shovel-nose modification was eventually removed after World War II, restoring its original boxcab appearance.

In the GM&O years, the locomotive shifted primarily to local freight and secondary passenger duties. By the 1950s, it operated alongside more modern first-generation diesels. Its early design, while reliable, lacked the power, speed, and amenities of the newer EMD E-units and F-units that had become standard. It was retired from service in 1956 after roughly 21 years of operation.

Preservation at the National Museum of Transportation

Following retirement, GM&O donated the locomotive to the National Museum of Transportation (now often called the Museum of Transportation) in St. Louis, Missouri. It remains on static display there, preserved in its later boxcab configuration.

The unit received special recognition in 1972 when it was photographed at the EMD plant in La Grange, Illinois, during celebrations of Electro-Motive’s 50th anniversary. This underscored its historical importance as one of the very first production road diesels.

Today, visitors can view #50 alongside other pioneering diesels, including early switchers and streamliners. It serves as an educational artifact illustrating the transition from steam to diesel power.

Technical Specifications

Here is a compiled HTML table of key specifications for B&O #50 (based on historical records for the EMC 1800 hp B-B class):

Baltimore & Ohio #50 – EMC 1800 hp B-B Boxcab Diesel Specifications
Parameter	Specification	Notes
Builder	Electro-Motive Corporation (EMC); carbodies by General Electric (Erie, PA)	Design by EMC; one of five experimental units built in 1935
Build Date	August 1935	Serial number 532; Order E127
Model / Type	EMC 1800 hp B-B experimental boxcab	Testbed / road diesel; dual-end control cabs
Wheel Arrangement	B-B (AAR classification)	Two two-axle powered trucks; all axles driven
Power Output	1,800 hp (1,342 kW)	Total from two engines
Prime Movers	Two Winton 201-A V12 diesel engines	Each rated 900 hp (670 kW); early diesel technology
Transmission	Diesel-electric	Generators powering traction motors
Length	Approximately 66 feet (20.1 m)	Classic boxcab proportions
Weight	Not precisely documented in primary sources (est. 200,000–250,000 lbs / 90–113 metric tons)	Comparable to contemporary experimental units
Tractive Effort	Not specifically recorded for this unit	Sufficient for named passenger trains of the era
Brakes	Westinghouse air brakes (locomotive and train)	Standard for the period
Fuel Capacity	Not documented in detail	Typical for early road diesels
Original Road Number	B&O #50	Later: Chicago & Alton #50; GM&O #1200
Disposition	Preserved	National Museum of Transportation, St. Louis, MO

Historical Significance

B&O #50 was more than just another locomotive—it was a technological bridge. While not the absolute first diesel in any service (earlier switchers existed), it was among the very first self-contained diesel-electric units placed in regular mainline passenger road service. Its success helped validate diesel power for high-profile trains and accelerated the industry-wide shift away from steam.

The design directly influenced the streamlined EMC EA/EB units that followed and the broader E-unit family that dominated passenger service for decades. The MU control system and twin-engine reliability concepts carried forward into production models.

In the broader context of the 1930s, #50 exemplified how railroads leveraged federal support (PWA) and private innovation to survive economic turmoil. Its preservation ensures future generations can appreciate this pivotal moment when the diesel revolution began reshaping American railroading.

Today, standing quietly in St. Louis, B&O #50 reminds us of an era when bold engineering choices transformed transportation. From hauling the Royal Blue in the 1930s to its quiet retirement in the 1950s, this pioneering boxcab earned its place in railroad history as a true trailblazer. Its story continues to inspire rail enthusiasts, historians, and anyone fascinated by the evolution of motive power.

Facebook X Pinterest Tumblr Reddit WhatsApp Messenger