City (pop., 2000: 123,975), southeastern South Dakota, U.S. Founded in 1857, the area was abandoned in 1862 following an Indian uprising.
With the establishment of Fort Dakota on the site in 1865 the settlers gradually returned. Sioux Falls is the state's largest city, and it is a commercial and financial centre in a livestock-farming region, with one of the largest livestock markets in the U.S. Nearby was one of the world's first commercial nuclear power plants, decommissioned in 1967. The Earth Resource Observation Systems (EROS) Data Center is located in the city.