Carlisle is a borough in Cumberland County, Pennsylvania, 18 miles (29 km) west by southwest of Harrisburg, the state capital. The name is traditionally pronounced with emphasis on the second syllable. Carlisle is located within the Cumberland Valley, a highly productive agricultural region. As of the 2000 census, the borough population was 17,970. It is the county seat of Cumberland County. Carlisle is the smaller principal city of the Harrisburg–Carlisle Metropolitan Statistical Area, which includes all of Cumberland, Dauphin, and Perry counties.