Sioux Falls (pronounced "sue falls") is a city in the U.S. state of South Dakota. It is the largest city in the state; 153,888 people lived there at the 2010 census. The city is in the eastern part of South Dakota. It is the county seat of Minnehaha County, where most of the city is located. The southern part of the city is in Lincoln County. Sioux Falls became a city in 1876. The city is built around the Big Sioux River, and it gets its name from a set of waterfalls along the river that are located in a park in the city.