RIDGE AND VALLEY

physiographic province, part of the Appalacian Highlands in the eastern United States. It is bordered on the east by the Blue Ridge and Piedmont provinces and on the west by the Appalachian Plateau. As its name implies, the province is a series of alternating ridges and valleys extending for nearly 1,200 miles (1,930 km) from the St. Lawrence Valley in upstate New York to the Coastal Plain of central Alabama. Its width varies from 14 to 80 miles (23 to 130 km). In the north, the Hudson Valley section extends southward along the Hudson River valley from the VermontNew York border and southwestward along Kittatinny Mountain into eastern Pennsylvania. The Middle section curves through central Pennsylvania, western Maryland, and eastern West Virginia to the Tennessee Valley Divide in western Virginia and includes the renowned Shenandoah Valley of northern Virginia. The Great Valley that is central to this section continues southwestward as the Tennessee, or Southern, section.