Deer Lodge is an incorporated city in and the county seat of Powell County, Montana, in the United States. The population was 3,111 at the 2010 census. 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 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. Deer Lodge was also once an important railroad town, serving as a division headquarters for the Chicago, Milwaukee, St. Paul and Pacific Railroad ("the Milwaukee Road") before the railroad's local abandonment in 1980.
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.
Deer Lodge is also the location of Grant-Kohrs Ranch National Historic Site, dedicated to the interpretation of the frontier cattle ranching era. This site was the home of Conrad Kohrs, one of the famous "Cattle Kings" of Montana whose land holdings once stretched over a million acres (4,000 km2) of Montana, Wyoming, and Alberta, Canada. The Grant-Kohrs ranch was built in 1862 by Johnny Grant, a Scottish/French/Metis fur-trader and trapper who encouraged his people to settle in Deer Lodge because of its pleasant climate and large areas of bunch grass prairie, ideal for raising cattle and horses. The city's 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.
Deer Lodge was the site of the College of Montana, the first institution of higher learning in the state.