Outline of Illinois
The following outline is provided as an overview of and topical guide to the U.S. state of Illinois:
Illinois – fifth most populous of the 50 states of the United States of America. Illinois lies between Lake Michigan and the Mississippi River and the Ohio River in the Midwestern United States. Chicago, Illinois, is the third most populous city and the third most populous metropolitan area of the United States. The United States created the Illinois Territory on March 1, 1809. Illinois joined the Union as the 21st state on December 3, 1818.
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