Tennessee is divided into six major physical regions: the Unaka Mountains, the Great Valley of East Tennessee, the Cumberland Plateau, the Highland Rim, the Central Basin, and the Gulf Coastal Plain. In addition, there are two minor physical regions: the Western Valley of the Tennessee River and the Mississippi Flood Plains.
The Unaka Mountains, part of the Appalachian chain includes several ranges of which the most notable is the Great Smoky Mountains. The region constitutes the highest and most rugged surface in the state and covers an area of about 2,600 sq mi (6,700 sq km). The tallest peak Clingmans Dome in the Great Smokies is at a height of 6,643 ft (2,026 m). It is also the highest point of the state.
The Great Valley of East Tennessee extends from southwestern Virginia into northern Georgia. The Great Valley is a segment of the Ridge and Valley province of the Appalachian Highlands, which reach from New York into Alabama. This region, consisting of long, narrow ridges with broad valleys between them, covers more than 9,000 sq mi (23,000 sq km) of Tennessee. The area is surrounded with artificial lakes and dams that supply electric power and aid in flood control.
The Cumberland Plateau, which extends in its entirety from southern Kentucky into central Alabama, has an area of about 5,400 sq mi (14,000 sq km) in Middle Tennessee. The plateau includes both the Cumberland Mountains, which rise to a height of 3,500 ft (1,100 m), and the Sequatchie Valley, which lies about 1,000 ft (300 m) below the surface of the adjoining plateau.
The Highland Rim, also in Middle Tennessee, is the state's largest natural region, consisting of more than 12,500 sq mi (32,400 sq km) and encircling the Central Basin. The eastern section is a gently rolling plain some 1,000 ft (300 m) lower than the Cumberland Plateau while the western part has an even lower elevation and sinks gently toward the Tennessee River.
The Central Basin has rich fertile soil and has attracted people from the days of the European settlement and is more densely populated than any other state.
The Gulf Coastal Plain is the westernmost region of the state and covers an area of 9,000 sq mi (23,000 sq km). It is a broad plain, sloping gradually westward until it ends abruptly at the bluffs overlooking the Mississippi Flood Plains. In the northwest corner is Reelfoot Lake, the only natural lake of significance in the state, formed by a series of earthquakes in 1811 and 1812. The state's lowest point, 178 ft (54 m) is on the banks of the Mississippi in the southwest.
Most of the state is drained by the Mississippi River system. Waters from the two longest rivers—the Tennessee and the Cumberland flow into the Ohio River in Kentucky and join the Mississippi at Cairo, Illinois. The Cumberland River rises in southeastern Kentucky, flows across central Tennessee, and then turns northward back into Kentucky. The main tributaries of Cumberland are the Harpeth, Red, Obey, Caney Fork, and Stones rivers and Yellow Creek. In the western part of the state, the Forked Deer and Wolf rivers are among those flowing into the Mississippi, which forms the western border with Missouri and Arkansas.