The St. Croix River headwater is in Douglas County, Wisconsin south of Lake Superior. 125 miles of its southerly flow defines the border between Minnesota (on the left) and Wisconsin (on the right) until it becomes a tributary of the Mississippi River in Prescott, Wisconsin near St. Paul, Minnesota. The Dakota people called the river Ouadeba. The Ojibwe named it Jiibayaatig-ziibi. When Missionary Father Louis Hennepin discovered it in 1683, he referred to it as River of the Grave. It was renamed Rivière de Sainte-Croix in 1688 by cartography Jean-Baptiste-Louis Franquelin while mapping New France. This French colony included the Great Lakes until the land was relinquished in 1763 with the signing of the Treaty of Paris.