Ranges of the Appalachian system in Pennsylvania, Maryland, Virginia, and West Virginia, U.S., west of and generally parallel to the Blue Ridge Mountains.
They extend some 500 mi (800 km) south-southwestward, with heights of more than 4,800 ft (1,460 m). The eastern slope is sometimes called the Allegheny Front, while the Allegheny Plateau spans the entire upland area from the Cumberland Plateau to the Mohawk Valley in New York.