Construction on the U.S. Route 66, known as the "Mother Road", began in 1926 and eventually the 2,448 mile highway would cross through eight states on its way from Chicago to Santa Monica, California. In Illinois, and the Midwest in general, the construction of U.S. Route 66 was important to the economies of small, rural towns, which saw a burst of activity when the road finally passed through.
Route 66 originally followed the already in-use Illinois State Route 4 north of Hamel. The route navigates through Staunton, Sawyerville, Benld, Gillespie, Carlinville, to Nilwood. Route 4/Route 66 from Nilwood to Girard was listed on the U.S. National Register of Historic Places on May 23, 2002. Route 66 continues along Route 4 north through Virden, Thayer, to Auburn. A section of Illinois Route 4 north of Auburn, and south of Springfield, which was also part of the original span of U.S. 66, was listed on the National Register of Historic Places on August 6, 1998. This is the last brick alignment in Illinois. Route 66 passes through Chatham, and enters Springfield. Breaking off of U.S. 4, the route passes the Illinois State Capitol and the Old State Capitol.