Culturally and physically distinct mountainous region extending from western New York and Pennsylvania to northern Mississippi and Alabama. Definitions of the region vary. Physiographically, the Appalachian mountain system trends northeast-southwest from Maine to northern Alabama. Components include the Blue Ridge in the east; the Great Valley, including the Shenandoah, James, New, and Tennessee valleys; the Ridge and Valley; and to the west the Allegheny/Appalachian/Cumberland Plateau. (See map). Politically, the "Appalachian region" consists of the 406 counties in 13 states under the jurisdiction of the federal government body, the Appalachian Regional Commission, established in 1965 to serve a region that included some of the most impoverished areas of the U.S. West Virginia is the only state that falls entirely within the region.