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Downstate Illinois is all of Illinois south of the Chicago metropolitan area, and is generally meant to refer to everything outside the Chicago area. Some cities in Northern Illinois, such as Rockford    (which is north of Chicago), are also considered to be "downstate".   Prior to the issuance of 2000 Census results, when it became part of the Chicago metropolitan area, even DeKalb (located 65 miles west of Chicago) was often considered to be "downstate".   
The term has been part of the Illinois lexis for decades,  and is commonly used by the media.    The General Assembly (the state legislature for Illinois) regularly uses the term in the titles of bills it passes. 
|Ten Largest Downstate Cities|
Most of the state's largest cities (six of the top ten) are concentrated in and around the Chicago area, but several mid-sized cities exist in the downstate area as well.
- Upstate New York, an area similar to Downstate Illinois
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