The north span consists of the portion of the ridge from the Potomac to the town of Hedgesville, West Virginia, which lies 3.5 miles (5.6 km) to the south within Skinners Gap in between the mountain's two spans.

The southern span consists of the remaining 20 miles (32 km) of ridge line and is noticeably higher in elevation, containing the mountain's highest point of 1,673 feet (510 m) above sea-level at its Roundtop summit near Arden in Berkeley County, West Virginia.

The southern section also contains many gaps, but all are several hundred feet above the valley floor.

Back Creek owes its name to North Mountain, as early settlers in the eighteenth century referred to the stream as to the "back" of the ridge when approaching it from the east.

The Roundtop summit was the location of Cowpuncher, a Presidential Emergency Facility serving Washington, D.C., during the Cold War.