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 (38,200 km2) in Minnesota and about 2,000 sq mi (5,200 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. Of Dakota language origin, the name Minnesota means "sky-tinted water or cloudy-sky water", from mní (often transcribed as "minne" or "mini") meaning "water" and sóta meaning "sky-tinted" or "cloudy sky", and, refers to the milky-brown color its waters take on when at flood stage. An illustration of the meaning of these words was shown by dropping a little milk into water. For over a century prior to the organization of the Minnesota Territory in 1849, the name St. Pierre (St. Peter) had been generally applied to the river by French and English explorers and writers. Minnesota River is shown on the 1757 edition of Mitchell Map as "Ouadebameniſsouté [Watpá Mnísota] or R. St. Peter". On June 19, 1852, acting upon a request from the Minnesota territorial legislature, the United States Congress decreed the aboriginal name for the river, Minnesota, to be the river’s official name and ordered all agencies of the federal government to use that name when referencing it.