In the era of steam locomotives, roundhouses were commonly found in rail yards across the country. With the exception of switching locomotives, steam locomotives were designed to run in one direction -- forward. As a result, it was often necessary to turn a steam locomotive to point in the direction its train is to be hauled. This was done by either use a wye, a balloon loop, or a turntable. The combination of turntable and roundhouse proved very useful to both service and turn locomotives.
Many roundhouses were built around the turn of the century. Roundhouses were built out of brick, stone, wood, or concrete. They could have only a few stalls or as many as 50. Locomotives would be serviced with the front of the locomotive pointing outward and the tender of the locomotive facing the turntable. Each stall of the roundhouse included a vent that would allow smoke from the steam locomotive to be vented to through the roof of the roundhouse. These vents can be clearly seen in most surviving roundhouses.
With the arrival of diesel locomotives, which could run equally well in either direction, the need for turntables (and roundhouses) waned. By the 1950s, as most steam locomotives had been replaced by diesels, the roundhouse became obsolete.
Today, most roundhouses are gone. However, a number survive. A few have been restored and are now used as restaurants or museums. Once such example is the Baltimore and Ohio's Mt. Claire roundhouse which now serves as the B&O Railroad Museum.
If you know of a roundhouse not shown in this list, feel free to submit its location using the form at the bottom of one of the state pages.
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