ASME-Landmark:Baltimore & Ohio

During World War I, American railroads were placed under the control of the United States Railroad Administration (USRA). To facilitate construction, operation, and maintenance, all new steam locomotives ordered during this period were built to one of twelve standard designs developed by a committee composed of representatives from USRA, the railroad industry, and locomotive-builder companies. This family of locomotives, ranging from 0-6-0 to 2-8-8-2 in size, incorporated the best proven features of the day and was the first successful standardization of American motive power. More than 1,800 locomotives were placed in service during the war effort. Although the USRA period lasted only three years, locomotives continued to be built around these basic designs for another decade.

Baltimore & Ohio (B & O) 4500, built by Baldwin Locomotive Works, was the first USRA locomotive built. It is a "light Mikado," the most common USRA freight design. B&O assigned the 4500 Class Q-3 and acquired more than 100 of these 2-8-2s.

The 4500 was built in 20 days, a record for any locomotive of similar capacity, but probably a result of overtime labor. As the prototype USRA locomotive, it has a flatter roof cab design than later engines and was built without front-end ladders, which later engines had. The 4500, which was in service for almost 40 years, was retired August 1957 and put on display at the B & O Railroad Museum in 1964. It remains essentially as built. See ASME website for more information