The Montana State Prison is a men's correctional facility of the Montana Department of Corrections in unincorporated Powell County, Montana, about 3.5 miles (5.6 km) west of Deer Lodge. The current facility was constructed between 1974 and 1979 in response to the continued degeneration of the original facility located in downtown Deer Lodge.
The "Old Prison" served as the Montana Territorial Prison from its creation in 1871 until Montana achieved statehood in 1889, then continued as the primary penal institution for the State of Montana until 1979. Throughout the prison's history, the institution was plagued with constant overcrowding, insufficient funds, and antiquated facilities. The administration of Warden Frank Conley from 1890 to 1921 proved the exception to this rule, as Warden Conley instituted extensive inmate labor projects that kept many inmates at work constructing the prison buildings and walls as well as providing various state and community services like road building, logging, and ranching.
After Conley left office, the prison experienced almost forty years of degeneration, mismanagement, and monetary restraints until an explosive riot in 1959 captured the attention of the nation. Led by Jerry Myles and Lee Smart, the riot maintained the prison under inmate control for thirty-six hours before the Montana National Guard stormed the institution to restore order. The facility was retired in September 1979, and the inmates were moved to the current prison. The Old Prison was added to the National Register of Historic Places in 1976 and is now a museum.