U.S. Route 66 originally followed IL 4 north of Hamel. This alignment navigated through Staunton, Sawyerville, Benld, Gillespie and Carlinville to Nilwood. The section of US 66/IL 4 from Nilwood to Girard was listed on the National Register of Historic Places on May 23, 2002. Route 66 continues along IL 4 north through Virden, Thayer, to Auburn. A section of IL 4 north of Auburn and south of Springfield, which was also part of the original span of US 66, was listed on the National Register of Historic Places on August 6, 1998. This is the last brick alignment in Illinois. Route 66 then passed through Chatham, and entered Springfield. Breaking off of IL 4, the route passed the Illinois State Capitol and the Old State Capitol.