Great Appalachian Valley

Also called  Great Valley Region,   longitudinal chain of valley lowlands of the Appalachian mountain system of North America. Extending from Canada on the northeast to Alabama, U.S., on the southwest, it includes the St. Lawrence River valley in Canada and the Kittatinny, Cumberland, Shenandoah, and Tennessee river valleys in the United States. In its southerly region the Great Appalachian Valley divides