The Wisconsin River is a tributary of the Mississippi River in the U.S. state of Wisconsin. At approximately 430 miles (692 km) long, it is the state’s longest river. The river’s name, first recorded in 1673 by Jacques Marquette as “Meskousing,” is rooted in the Algonquian languages used by the area’s American Indian tribes, but its original meaning is obscure. French explorers who followed in the wake of Marquette later modified the name to “Ouisconsin,” and so it appears on Guillaume de L’Isle’s map (Paris, 1718) This was simplified to “Wisconsin” in the early 19th century before being applied to Wisconsin Territory and finally the state of Wisconsin.
The Wisconsin River originates in the forests of the Lake District of northern Wisconsin, in Lac Vieux Desert near the border of the Upper Peninsula of Michigan. It flows south across the glacial plain of central Wisconsin, passing Wausau and Stevens Point. In southern Wisconsin it encounters the terminal moraine formed during the last ice age, where it forms the Dells of the Wisconsin River. North of Madison at Portage, the river turns to the west, flowing through Wisconsin’s hilly Western Upland and joining the Mississippi approximately 3 miles (4.8 km) south of Prairie du Chien. Although the river was originally navigable up to the city of Portage 200 miles (320 km) from its mouth, it is now considered non-navigable beyond the lock and dam at Prairie du Sac.1
The Wisconsin river at Sauk Prairie.