Illinois State Route 251 is the main north-south surface route through Winnebago County, east of the Rock River. This highway connects the north and south sides of the Rockford-Metro to Downtown Rockford. IL St Rt 251 passes through the following towns in Winnebago County. Rockford
A Winnebago County mile marker. A BGS on EB U.S. Rt. 20. A junction marker on SB U.S. Rt. 51. Looking south at the northern start point. The northern end marker.