The Minnesota River is a tributary of the Mississippi River, approximately 332 miles (534 km) long, in the U.S. state of Minnesota. It drains a watershed of nearly 17,000 square miles (44,000 km2), 14,751 square miles (38,205 km2) in Minnesota and about 2,000 sq mi (5180 km2) in South Dakota and Iowa. It rises in southwestern Minnesota, in Big Stone Lake on the Minnesota–South Dakota border just south of the Laurentian Divide at the Traverse Gap portage. It flows southeast to Mankato, then turns northeast. It joins the Mississippi south of the Twin Cities of Minneapolis and St. Paul, near the historic Fort Snelling. The valley is one of several distinct regions of Minnesota. As shown on old maps of Fort Snelling, early explorers dubbed the waterway the St. Pierre or St. Peter's River. Pierre-Charles Le Sueur was the first European to visit the river, but there is no consensus as to the origin of its original name. Its name comes from the Lakota language mini meaning "water" and sota which is alternately translated "smoky-white" or "like the cloudy sky". Minnesota Territory, and later the state, were named for the river.