Illinois was the first of Route 66’s eight states to complete its section of the highway.
When Route 66 was designated, much of its Illinois alignment already consisted of paved roads. The route followed earlier corridors, including the Pontiac Trail and roads improved under federal-aid programs. This gave Illinois a head start over states where Route 66 still crossed gravel or dirt surfaces.
The Illinois segment ran for about 301 miles between the St. Louis area and Chicago. It passed through communities such as Springfield, Bloomington-Normal, Pontiac, Joliet, and several Chicago suburbs. The road brought travelers, freight, restaurants, filling stations, and other businesses to towns along its path.
Illinois is sometimes overlooked because Route 66 is strongly associated with the Southwest. However, the highway began in Chicago, and the state played an important role in its early development. The Illinois section also illustrates that Route 66 was largely a network of older roads joined into a national route, not a completely new highway built from scratch.