An area of just over 77,000 square miles puts South Dakota in the largest third of the states in terms of size ranking by land. This sparsely-populated state is home to only about 10 people per square mile, offering a dearth of natural scenery and wild terrain. South Dakota's topography varies widely, from gently rolling plains, to deep river valleys, barren hills and forested mountains, allowing visitors the chance to explore quite diverse landscapes.
The vast Great Plains of North America stretch east-to-west from the Appalachian Mountains to the Rocky Mountains, and south-to-north from Mexico to the Arctic, covering parts of 10 states and three Canadian provinces. The Great Plains are technically a plateau, an elevated, but mostly flat, landform. These semiarid grasslands cover nearly three-quarters of South Dakota, breaking into buttes -- steep, flat-topped hills -- in some areas, particularly toward the western part of the state.
In the far northeast of the state, the Red River forms South Dakota's border with Minnesota. The land adjacent to this river sits at about 1,000 feet, a lower elevation than that of the surrounding plateau of the Great Plains. The southward-flowing James River cuts through the heart of eastern South Dakota, and the fertile valley flanking its banks makes this narrow band of land the most productive agricultural area in the state. Elevations here range from 1,300 to 1,400 feet, higher than the Red River Valley, but still lower than the surrounding Great Plains. The valley cut by the Missouri River is, at only one-mile-wide, extremely narrow; hence, it is known as the Missouri River Trench. Bluffs rise sharply upward 300 to 600 feet along the edges of this trench.
A series of buttes and dome-like, rolling hills known as the Badlands cover 2,000 square miles along the western edge of the Great Plains in South Dakota. Very little vegetation grows in this barren, rugged landscape. Once home to exotic animal species such as camels and saber-toothed tigers, much of the Badlands are now part of the protected Badlands National Park.
West of the Badlands, the Black Hills straddle the Wyoming border. Unlike the Badlands, however, forests cover these dome-shaped mountains, constituting the Black Hills National Forest. The famed Mt. Rushmore is carved into one of their rocky promontories. Near the center of the range, Harney Peak rises to 7,242 feet -- not only the highest point in South Dakota, but the highest point in the United States east of the Rocky Mountains.
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