Deer Lodge is a city in and the county seat of Powell County, Montana, United States. The city is perhaps best known as the home of the Montana State Prison, a major local employer. The Montana State Hospital in Warm Springs, and former state tuberculosis sanitarium is in nearby Galen are the result of the power the western part of the state held over Montana at statehood due to the copper and mineral wealth in that area. The city name derives from a geological formation known as Warm Springs Mound which contained natural saline that made for a natural salt lick for the local deer population, the protected valley in which Deer Lodge is located was where most of the local wildlife would winter as the temperatures lowered in the high country.
The current Montana State Prison occupies a campus 3.5 miles (5.6 km) west of town. The former prison site, at the south end of Deer Lodge's Main Street, is now the Old Prison Museum. In addition to a former cellblock building, the museum complex includes a theater, antique and automobile museums, and a former Milwaukee Road "Little Joe" electric locomotive.