US Route 66 in Illinois

U.S. Route 66 (US 66, Route 66) was a United States Numbered Highway in Illinois that connected St. Louis, Missouri, and Chicago, Illinois. The highway had previously been Illinois Route 4 (IL 4) and the road has now been largely replaced with Interstate 55 (I-55). Parts of the road still carry traffic and six separate portions of the roadbed have been listed on the National Register of Historic Places.