Corrections Secretary John Wetzel planned a Wednesday morning announcement.
Benner State Prison in Centre County can house 2,000 inmates, but it's been vacant since being completed a year ago. The prisons being closed are Greensburg State Prison in Westmoreland County and Cresson State Prison in Cambria County.
State Sen. Kim Ward of Westmoreland County says she wants hearings on the matter to learn how the state came to its decision.
The state counts more than 51,000 inmates, including about 2,400 in county jails or community correctional centers. Roy Pinto of the Pennsylvania State Corrections Officers Association says the system was built to handle well below 40,000 inmates.