Outline Map of Illinois
This map is a basic black and white map showing the county lines as its only details.
Source: Indiana State University

Illinois State Map
If you need a map that shows the major freeways in Illinois, this is it!
Source: World Sites Atlas

Annual Average Precipitation Map
This map shows the average annual rainfall in the state.
Source: Spatial Climate Analysis Service, Oregon State University

Illinois Census Map
Get information about population distribution in the State of Illinois from this website Click on 'view map' and see how it all breaks down by county.
Source: U.S. Census Bureau

Merriam Webster Atlas
This atlas page shows the Illinois state map and some quick facts. There is also a good explanation of the symbolism of the state flag.
Source: The New York Times and Merriam Webster