In General (Entire State)
- Illinois State Historical Society
- At Home in the Heartland from the Illinois State Museum
- History of Illinois – Wikipedia Entry
- Illinois History Magazine from the Illinois Historic Preservation Agency
- Illinois Genealogy & History from the United States Genealogy Network
- Illinois History from the ILGenWeb Project
- Chronology of Illinois History (PDF) from the Illinois Blue Book
- Illinois History Blog
- Illinois History from History.com
- Illinois Counties & Incorporated Municipalities (Illinois Secretary of State, May 2006)
Specific Locations
- Central Illinois History from the Peoria Journal-Star
- History of Southern Illinois from Mardos Memorial Library
- Southern Illinois History
- DuPage County History & Genealogy
- Randolph County History
- History of Counties in Western Illinois
- Encyclopedia of Chicago