Mercersburg is a borough in Franklin County, Pennsylvania, 73 miles southwest of Harrisburg. Originally called Black Town, it was incorporated in 1831. In 1900, 956 people lived here, and in 1910, 1,410 people lived here. The population was 1,540 at the 2000 census. Mercersburg apartments for rent comparison page shows most up to date rent information on Mercersburg apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.