Illinois Route 73
|Maintained by IDOT|
|Length:||29.32 mi (47.19 km)|
|Existed:||1924 – present|
|South end:||US 52 / IL 64 in Lanark|
|US 20 in Lena|
|North end:||CTH M in Winslow|
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).
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 state highway that does not either continue as another state highway, or end at a ferry crossing (current or former).