Rock River
The Rock River begins in Wisconsin, where three branches meet at Horicon Marsh, and flows south through Illinois to the Mississippi at Rock Island.
Where the Rock River flows
The river runs through or along these 10 counties: Dodge County; Jefferson County; Rock County; Henry County, IL; Lee County, IL; Ogle County, IL; Rock Island County, IL; Scott County, IA; Whiteside County, IL; Winnebago County, IL.
Towns and cities within about 2 miles of the river, by county:
- Dodge County Ashippun, Horicon, Hustisford
- Jefferson County Fort Atkinson, Ixonia, Jefferson, Johnson Creek, Watertown, Watertown
- Rock County Afton, Beloit, Edgerton, Janesville
- Henry County, IL Colona
- Lee County, IL Dixon
- Ogle County, IL Byron, Oregon
- Rock Island County, IL Barstow, Carbon Cliff, Coal Valley, Hampton, Rock Island
- Whiteside County, IL Erie, Galt, Lyndon, Rock Falls, Sterling
- Winnebago County, IL Loves Park, Machesney Park, Rockford, Rockton, Roscoe, South Beloit
Counties from U.S. Census boundaries, places from a public U.S. cities list. Small communities may be missing.
River facts
| Length | About 299 miles |
|---|---|
| Source | Three branches converging at Horicon Marsh, Dodge County |
| Mouth | Mississippi River at Rock Island, Illinois |
| States | Wisconsin and Illinois |
| Main tributaries | Crawfish, Bark, Yahara, Pecatonica and Kishwaukee rivers |
There are 13 dams on the Wisconsin stretch, including at Theresa, Mayville, Watertown and Jefferson. Lake Koshkonong is a wide pool of the river.
Lakes and flowages on the Rock River
Lakes in our guide on or connected to this river:
Source: Rock River (Mississippi River tributary) (Wikipedia)