Marienville is a census-designated place located in Jenks Township, Forest County, Pennsylvania, United States. Its altitude is 1,732 feet (528 m), and it is located at 41°28′12″N 79°7′29″W / 41.47000°N 79.12472°W (41.4702014, -79.1247623). Other names for the community have included "Marion," "Marion Centre," and "Marionville." Marienville is a major point on a well-known ATV trail. According to the 2010 census the population of Marienville was 3,137.
On September 29, 2004, Corrections Secretary Jeffrey A. Beard, Ph.D., and General Services Secretary Donald T. Cunningham Jr. joined approximately 150 local, state and federal officials and dignitaries to formally dedicate the State Correctional Institution (SCI) at Forest, Forest County. The new, state-of-the-art maximum-security prison, which is situated on approximately 64 acres (260,000 m2), was scheduled to begin housing adult male inmates in October or November 2004. Built at a cost of $138 million, the prison houses approximately 2,200 inmates and employs 650 individuals at full operation. According to state officials, the prison represents great opportunity for economic revitalization in Forest County and the surrounding communities.