Minnesota River is a large branch of the Mississippi River. The Minnesota flows through a wide valley that was cut by the outlet of Lake Agassiz, an ancient glacial lake (see Lake Agassiz ). The Minnesota River rises in the Coteau des Prairies (Little Hills of the Prairie), a group of hills that are located in northeastern South Dakota. The river flows southeast to Big Stone Lake on the boundary between South Dakota and Minnesota. It follows Big Stone Lake south to Ortonville. There, the Minnesota River flows southeast to Mankato, Minnesota. The river then turns sharply to the northeast. It flows northeast until it joins the Mississippi River. The Minnesota River enters the Mississippi River south of St. Paul, Minnesota.
The Minnesota River is 332 miles (534 kilometers) long. It drains an area of about 16,600 square miles (41,400 square kilometers).
Early explorers and fur traders sailed up the Minnesota River in their westward journeys. Today, the river is an important trade route.
