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 km2) and an estimated population of just over 800,000. Pierre is the state capital and Sioux Falls, with a population of just over 150,000, is South Dakota's largest city.