The Fox River is a river in eastern Wisconsin in the Great Lakes region of the United States. It is the principal tributary of the Green Bay, and via the bay, the largest tributary of Lake Michigan. The city of Green Bay, one of the first European settlements in the interior of North America, is on the river at its mouth on the Green Bay.
Hydrographers divide the Fox into two distinct sections, the Upper Fox River, flowing from its headwaters in south-central Wisconsin northeasterly into Lake Winnebago, and the Lower Fox River, flowing from Lake Winnebago northeasterly to the Green Bay. Together, the two sections give the Fox River a length of 182 miles (293 km). Counting the distance through Lake Winnebago gives a total of 200 miles (322 km).
