Illinois Route 173 (IL 173) is a 66.20-mile-long (106.54 km) east–west state highway that runs from Illinois Route 251 in the Rockford suburb of Machesney Park east to Illinois Route 137 (Sheridan Road/Buckley) in Zion near the Illinois-Wisconsin border. Illinois Route 173 is also one of the northernmost east-west state highways in Illinois. On Interstate 94 (Tri-State Tollway) traveling south from Wisconsin, it is the second road seen which has an interchange at that location. Similarly, when traveling south/east from Wisconsin on Interstates 39/90 and U.S. Route 51 (Jane Addams Memorial Tollway), Illinois Route 173 is only the third exit into Illinois. In 2008, the entirety of Illinois 173 has been designated the 173rd Airborne Brigade Highway From Wikipedia
