northernmost section of the Blue Ridge in the Appalachian Mountains, extending southwestward for 65 miles (105 km) from southern Pennsylvania to northern Virginia, U.S. Quirauk Mountain (2,145 feet 【654 m】) in Maryland is the highest point. It is crossed by the Appalachian Trail (for hikers). The American Civil War Battle of South Mountain took place near Burkittsville, Md., on Sept. 14, 1862.