The Rock River begins in southern Wisconsin and flows south through Rockford, heading west passing by Sterling and Dixon ending in the Quad Cities area emptying into the Mississippi River.

The river gives rise to several recreation areas including Rock Cut State Park, Lowden State Park, Castle Rock State Park, Prophetstown State Park and Big Bend SFWA. In addition, from the Wisconsin border to Grand Detour, it has some of the best smallmouth bass fishing in the state.