South Dakota is a state located in the Midwestern region of the United States of America. It is named after the Lakota and Dakota (Sioux) American Indian tribes. South Dakota was admitted to the Union on November 2, 1889. (North Dakota was admitted simultaneously.)

Located in the north-central United States, South Dakota is bisected by the Missouri River, dividing the state into two socially and economically distinct halves, known to residents as "West River" and "East River." In the southwestern portion of the state rise the Black Hills, a group of low, pine-covered mountains. A region of great religious importance to local American Indians as well as a major draw for the state tourism industry, the Black Hills are also the location of Mt. Rushmore, probably the best-known location in the state and a widely-used symbol of South Dakota.

Historically dominated by an agricultural economy and a rural lifestyle, South Dakota has recently sought to diversify its economy in an effort to attract and retain residents. The state is still largely rural, though, with one of the lowest population densities in the United States. The centrally-located city of Pierre serves as the state capital, and Sioux Falls, with 150,000 people, is the largest city in the state.