The Illinois Department of Transportation provides a detailed map of the state's roads and highways. The map includes details on principal routes, covered bridges, railroads, interstate rest areas and toll plazas across the state. It also shows an index of the villages and cities and their locations on the map.
The detailed road map of Illinois is in PDF format and requires an Adobe Acrobat Reader. Aside from the official highway map, the IDOT also provides general highway maps of each county, city and township. The site provides separate maps to show the annual average daily traffic on the State Primary system. The AADT map is also viewable on the interactive application operated by the IDOT.