^Officially, these are "correctional facilities," or "correctional institutions," the term "state prison" being reserved for the facility at Cedar Junction in Walpole.
This template pertains only to agencies that handle sentenced felons (with sentences over 1-2 years). In many states, pre-trial detainees, persons convicted of misdemeanors, and felons sentenced under state law to less than one year are held in county jails instead of state prisons.