plateau in the northeastern United States, extending from the Adirondacks in the north through New York, Pennsylvania, West Virginia, Ohio, Kentucky, Tennessee, and Alabama to the Gulf Coastal Plain in the south. It lies between the Central Lowlands to the west and the Ridge and Valley region to the east. Rock layers in the plateau are nearly horizontal, and both anthracite and bituminous coal are extracted by drift mining. The Appalachian coalfields are the largest in the country and supply the steel industries in the northeast, including Pittsburgh. Other important minerals are iron ore, limestone, petroleum, and natural gas. The scenic landscape includes several national parks and forests. The Great Smoky Mountains National Park and other recreation areas attract many thousands of visitors every year.