Chambersburg is a borough in and the county seat of Franklin County, in the South Central region of Pennsylvania, United States. It is in the Cumberland Valley, which is part of the Great Appalachian Valley, and 13 miles (21 km) north of Maryland and the Mason-Dixon line and 52 miles (84 km) southwest of Harrisburg, the state capital. According to the United States Census Bureau, Chambersburg's 2010 population was 20,268. When combined with the surrounding Greene, Hamilton, and Guilford Townships, the population of Greater Chambersburg is 52,273 people. The Chambersburg, PA Micropolitan Statistical Area includes surrounding Franklin County, and in 2010 included 149,618 people.
According to the Pennsylvania Department of Community and Economic Development, Chambersburg Borough is the thirteenth largest municipality in the Commonwealth of Pennsylvania and the largest Borough, as measured by fiscal size (2016). Chambersburg Borough is organized under the Pennsylvania Borough Code and is not a home-rule municipality.
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 relating 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, which led to accusations of war crimes.
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.