Illinois Route 43 runs north-south through Chicago and some suburbs to the north and south. It lies entirely within the Chicagoland area. Illinois Route 43 serves some of the western reaches of the Chicago city limits and a wide range of suburbs, up to Waukegan in the north and Frankfort in the south. In Chicago and points south, Illinois 43 is known as Harlem Avenue; however, it's known as Waukegan Road in the northern suburbs.
Illinois 43's northern end is a partial interchange with US Route 41 by Waukegan; the northern beginning is a ramp off of US Route 41 that crosses right over Illinois 120:
As it begins, Illinois 43 southbound provides a ramp for accessing Illinois 120: