Chambersburg is a borough in Pennsylvania, United States. It is 52 miles southwest of Harrisburg in the Cumberland Valley, part of the Great Appalachian Valley. The borough is the county seat of Franklin County, Pennsylvania. As of the 2000 census, the borough's population was 17,862. Chambersburg apartments for rent comparison page shows most up to date rent information on Chambersburg apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.