South Dakota is a U.S. state in the upper Midwestern United States. It is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large portion of the population and historically dominated the territory. As the southern part of the former Dakota Territory, South Dakota became a state on November 2, 1889, simultaneously with North Dakota. It is either the 39th or 40th state admitted to the union.
Humans have inhabited the area for several millennia, with the Sioux becoming dominant by the early 19th century. In the late 19th century, European-American settlement intensified after a gold rush in the Black Hills and the construction of railroads from the east. Encroaching miners and settlers triggered a number of Indian wars, ending with the Wounded Knee Massacre in 1890. Key events in the 20th century included the Dust Bowl and Great Depression, increased federal spending during the 1940s and 1950s for agriculture and defense, and an industrialization of agriculture that has reduced family farming.