Appalachians, or Appalachian Highlands, an upland area of eastern North America, chiefly in the United States, extending from eastern Canada to central Alabama. The entire system is almost 2,000 miles (3,200 km) long, and up to 300 miles (480 km) wide. The region's higher and rougher parts form the so-called Appalachian Mountains.
The geological structure of the highlands is complex. At various times, the region or parts of it were uplifted, worn down by erosion to almost level plains, and uplifted again. In some cases, ridgelike structures were formed by folding. From Canada to northeastern Pennsylvania, glaciers both eroded the surface and created new land-forms by depositing loose rock and gravel.
The Appalachians are usually divided into five major physiographic provinces: New England-Acadia; Piedmont Plateau; Blue Ridge; Ridge and Valley; and Appalachian Plateau.
begins in Newfoundland, Canada, and runs through the Maritime Provinces and the New England states to the Hudson River Valley. Most of the area is less than 2,500 feet (760 m) above sea level. Isolated summits and several ranges stand out over the rest of the area. Among these are the White Mountains of New Hampshire and the Green Mountains of Vermont. The highest point is Mount Washington, 6,288 feet (1,917 m), in the White Mountains. Rocky deposits and glacial lakes cover much of the region's surface. Coasts are rugged, highly indented, and dotted with small offshore islands. The Adirondack Mountains of northern New York State are usually considered part of the Appalachians. Geologically, they are an outlying part of the Canadian Shield.
low and worn down, extends from northern New Jersey to central Alabama along the southeastern flank of the Appalachians. Most of the Piedmont is less than 1,200 feet (365 m) above sea level. There are, however, several isolated domes—such as Stone Mountain, near Atlanta—that stand high above the plateau's surface.
Along the Piedmont's southeastern border is the fall line. Here, streams descend to lower elevations as they leave the Piedmont and continue onto the flat Atlantic Coastal Plain. There are many rapids and small waterfalls.
province, west of the Piedmont from southern Pennsylvania to northern Georgia, is the highest part of the Appalachians. Here are the Great Smoky, Black, and Blue Ridge mountains. Mount Mitchell, rising 6,684 feet (2,037 m) in the Black Mountains, is the highest point in the eastern United States.
province lies mainly west of the Blue Ridge. However, along the eastern edge is the Great Valley, which extends northward into Canada by way of the Hudson River Valley and the Lake Champlain lowland. The Great Valley includes the Cumberland and Shenandoah valleys.
West of the Great Valley, from northern Pennsylvania southward, ridges are long and steep-sided, with remarkably even crests. Paralleling the ridges and separating them are relatively deep valleys.
sometimes called Appalachia, is the westernmost part of the highlands. It extends from New York to Alabama. Upland areas here include the Allegheny Plateau, Catskill Mountains, and Cumberland Plateau. In most areas, streams have cut deep valleys, making the terrain rough.
The Appalachian Plateau slopes off gradually to the west. On the east, however, from central Pennsylvania to northeastern Alabama, there is a steep, eastward-facing escarpment, which is most pronounced in the Allegheny Front of Pennsylvania. The part of this high eastern margin that lies between Pennsylvania and Virginia is called the Allegheny Mountains.
In the decades after American independence was won, a rush began for the western lands beyond the Appalachians. To reach the frontier, pioneers used the valleys and gaps through the mountains. Among the more important routes were the Mohawk Valley of New York, where the Erie Canal was later built; the Potomac Valley, from which the Cumberland, or National, Road originated; and the Cumberland Gap, passageway for the Wilderness Road. Many of the routes are still used by railroads and highways.
Economic activities in this large area are extremely varied. They range from fishing, in isolated settlements on the Newfoundland coast, to the highly developed manufacturing and commerce of the New England and Middle Atlantic states. Farming is extensive in the United States section, especially on the Piedmont Plateau and in river valleys. Dairying is important. Fuels, notably coal and natural gas, are abundant in the Appalachian Plateau. In the south are valuable iron ore deposits and extensive stands of commercial timber, particularly hardwoods.
Despite the region's extensive natural resources, there are pockets of chronic poverty, especially in coal-mining areas and in some farmlands of the southern states.
The scenic beauty of mountains, streams, and forests makes the Appalachians a popular vacation area. Tourists are also attracted by the region's many historic sites.