Region
Mississippi River Watershed
United States
29
Minnesota
13
Wisconsin
11
Western Gulf of Mexico basins
6
Hudson Bay
3
Mexico, Gulf of
3
Mississippi River
3
Saint Lawrence River Watershed
3
Hudson Bay Watershed
2
Middle West
2
Missouri River Watershed
2
Hastings Region
1
Hudson River (N.Y. and N.J.)
1
Illinois
1
Illinois River
1
Royalton Region
1