💧 Big Sioux River

The Big Sioux River is a tributary of the Missouri River in eastern South Dakota and northwestern Iowa in the United States. It flows generally southwardly for 419 mi (674 km), and its watershed is 9,006 mi2 (23,330 km2). The United States Board on Geographic Names settled on "Big Sioux River" as the stream's name in 1931. The river is named after the Dakota people, who have known it as C̣aƞ Kaṡdéc̣a, or Wood Split by Striking.