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).

Route description

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).

History

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.

Major intersections

County	Location	mi	km	Destinations	Notes
Carroll	Lanark	0.00	0.00	US 52 / IL 64 – Mount Carroll, Brookville	Southern terminus of IL 73
		4.2	6.8	IL 72 – Shannon	Western terminus of IL 72
Stephenson	Lena	18.1	29.1	US 20 – Stockton, Freeport
	Winslow	29.32	47.19	CTH-M – Martintown	Continuation into Wisconsin
1.000 mi = 1.609 km; 1.000 km = 0.621 mi