Chambersburg is a borough in the South Central region of Pennsylvania, United States. It is 13 miles (21 km) miles north of Maryland and the Mason-Dixon line and 52 miles (84 km) southwest of Harrisburg in the Cumberland Valley, which is part of the Great Appalachian Valley. Chambersburg is the county seat of Franklin County. The United States Census Bureau estimates the population within the borough limits as of July 1, 2008, as 18,302. When combined with the surrounding Greene, Hamilton, and Guilford Townships, the population of Greater Chambersburg is 52,273. Chambersburg is at the core of the Chambersburg Micropolitan Statistical Area which includes surrounding Franklin County. The population of the Chambersburg Micropolitan Area in 2008 was 143,495.
Chambersburg's settlement began in 1730 when water mills were built at the confluence of Conococheague Creek and Falling Spring Creek that now run through the center of the town. Its history includes episodes related to the French and Indian War, the Whiskey Rebellion, John Brown's raid on Harpers Ferry, and the American Civil War. The borough was the only major northern community burned down by Confederate forces during the war.
Chambersburg is located along the Lincoln Highway, U.S. 30, between McConnellsburg and Gettysburg, Pennsylvania and along U.S. 11, the Molly Pitcher Highway, between Shippensburg, Pennsylvania, and Hagerstown, Maryland. Interstate 81 skirts the borough to its east.