South Mountain (Maryland and Pennsylvania)

South Mountain is the northern extension of the Blue Ridge Mountain range in Maryland and Pennsylvania. From the Potomac River near Knoxville, Maryland, in the south, to Dillsburg, Pennsylvania, in the north, the 70mi range separates the Hagerstown and Cumberland valleys from the Piedmont regions of the two states. The Appalachian National Scenic Trail follows the crest of the mountain through Maryland and a portion of Pennsylvania.GeographySouth Mountain begins at the Potomac River as a low, narrow ridge, barely one mile wide and only above sea level at its crest. South of the Potomac River in Virginia, the ridge continues as Short Hill Mountain for about before subsiding near the town of Hillsboro. South Mountain in Maryland gradually grows higher and wider towards the north. Near the Pennsylvania border, the mountain merges with the hills of the parallel Catoctin Mountain range to the east and becomes more like a low mountain range than a single crest. North of U.S. Route 30 in Pennsylvania, the South Mountain highlands reach their greatest width, over, and several summits top. The mountain then turns more to the east and becomes a series of small rocky hills between Mount Holly Springs and the northeastern end of the mountain at Dillsburg.