Geography of South Dakota - Regions

Regions

South Dakota can generally be divided into three regions: eastern South Dakota, western South Dakota, and the Black Hills. The Missouri River serves as a somewhat stark boundary in terms of geographic, social and political differences between eastern and western South Dakota, and the geography of the Black Hills differs from its surroundings to such an extent that it can be considered separate from the rest of western South Dakota. South Dakotans also at times combine the Black Hills with the rest of western South Dakota, and refer to the two resulting regions, divided by the Missouri, as West River and East River.

Eastern South Dakota is generally wetter and features lower topography than the western part of the state. Smaller geographic regions of this area include the Coteau des Prairies, the Dissected Till Plains, and the James River Valley. The Coteau des Prairies is a higher region bordered on the east by the Minnesota River Valley and on the west by the James River Basin. Numerous glacial lakes cover the Coteau, and it is largely drained by the Big Sioux River, a tributary of the Missouri. Further to the west, the James River Basin is mostly low, flat, highly eroded land, following the flow of the James River through South Dakota from north to south. The Dissected Till Plains, an area of rolling hills and fertile soil that covers much of Iowa and Nebraska, also extends into the southeastern corner of South Dakota.

The Great Plains cover most of the western two-thirds of South Dakota. The Coteau du Missouri lies between the James River Basin of the Drift Prairie and the Missouri River. This region is the southern section of a large plateau extending into Canada. West of the Missouri River the landscape becomes more rugged and consists of rolling hills, plains, ravines, and steep flat-topped hills called buttes. These buttes sometimes rise 400 to 600 feet (120 to 180 m) above the plains. In the south, east of the Black Hills, lie the South Dakota Badlands.

The Black Hills are in the southwestern part of South Dakota and extend into Wyoming. This range of low mountains covers 6,000 sq. miles (15,500 km².) with mountains that rise from 2,000 to 4,000 feet (600 to 1,200 m) above their bases. The highest point in South Dakota, Harney Peak (7,242 ft or 2,207 m above sea level), is in the Black Hills. This is the highest point in the United States east of the Rocky Mountains. Other Black Hills mountains that are over 7,000 ft (2,133 m) in elevation include Bear Mountain, Crooks Tower, Terry Peak, and Crows Nest Peak. The Black Hills are rich in minerals such as gold, silver, copper, and lead. The Homestake Mine, the largest and deepest gold mine in North America, is located in the Black Hills and has produced over $1 billion in gold since it started operation in 1876.