South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory South Dakota became a state on November 2 1889. The state has an area of 77 116 square miles (199 730 km) and an estimated population of just over 800 000. Pierre is the state capital and Sioux Falls with a population of nearly 160 000 is South Dakota's largest city.