Illinois Route 73 is a north–south state highway in northwest Illinois. It runs from the U.S. Route 52/Illinois Route 64 concurrency south of Lanark north to the Wisconsin border north of Winslow. This is a distance of 29.32 miles (47.19 km).[1]
Illinois 73 is a two-lane surface road for its entire length. At its northern terminus, Illinois 73 becomes County Highway M in Green County, Wisconsin. This is the only Illinois state highway that does not either continue as another state highway, or end at a ferry crossing (current or former).[2]
SBI Route 73 existed from Illinois Route 72 north of Lanark to Winslow. Around 1982, it replaced Illinois 72 from north of Lanark south to U.S. Route 52.[2]
