The Great Appalachian Valley of North America, a series of topographic valleys separated by low divides, stretches for more than 1200 miles, from the Richelieu Valley of Quebec (which drains Lake Champlain) to the Coosa River Valley of northeastern Alabama. While rivers have eroded (and continue to mold) the component valleys, geologic downwarping also shaped the terrain as adjacent mountains rose.
The eastern wall of the Valley is composed (from northeast to southwest) by the Green Mountains of Vermont, the Taconic Highlands of southern New England and the Blue Ridge Mountains, from south-central Pennsylvania through Virginia, North Carolina, Tennessee and northern Georgia. The west wall consists of the Adirondacks and Catskills of New York and the easternmost ridge of the Ridge & Valley Province, from Pennsylvania to Alabama. Some of America's most famous rivers course through sections of the Valley (including the Hudson, the Susquehanna, the Shenandoah and the Upper Tennessee) while others, such as the Mohawk, Potomac, Delaware and James Rivers, enter or cut across the Valley. Cities within the Valley include Burlington, Albany, Harrisburg, Hagerstown, Winchester, Harrisonburg, Bristol and Maryville, among others.
Indeed, the Great Appalachian Valley is not a closed basin and its walls are not continuous. Rather, rivers enter and leave the Valley through "water gaps" that formed as the mountains rose beneath the entrenched streams. Nevertheless, the "Great Valley," with its rich soil, diverse ecosystems and scenic vistas, has long provided a natural highway through mountainous terrain for wildlife, Native Americas and modern travelers alike.
