Sioux Falls is the most populous city in the U.S. state of South Dakota. It is the county seat of Minnehaha County and also extends into northern Lincoln County. The population was 192,517 at the 2020 census. The Sioux Falls metropolitan area, with an estimated 308,000 residents, accounts for more than one-third of South Dakota's population. Chartered in 1856 on the banks of the Big Sioux River, the city is situated in rolling hills at the junction of Interstates 29 and 90.