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This is a list of the area codes in the state of Illinois and the regions that they cover: *217: Central Illinois, running west from the Illinois-Indiana border through Danville, Effingham, Champaign–Urbana, Decatur, Springfield, Quincy until Illinois' western border with Iowa. *309: Central-Western Illinois including Bloomington–Normal, Peoria, and all the way west to the Illinois part of the Quad Cities including Moline, and Rock Island. *312: Chicago, the central city area including the Chicago Loop and the Near North Side. *630/331: West suburbs of Chicago in DuPage County and Kane County including Wheaton, Naperville, and Aurora. Area code 630 was overlaid with area code 331 in 2007. *618: Southern Illinois, including Carbondale and most of the Metro East region of St. Louis suburbs in Illinois *708: South suburbs and inner west suburbs of Chicago, including the Chicago Southland and most west and south suburbs in Cook County such as Oak Park, Oak Lawn, Chicago Heights, and Orland Park. *773: Chicago, covers most of the geographical area of Chicago except the downtown Chicago Loop, which is in area code 312. *815/779: Northern Illinois outside of the immediate Chicago area including Joliet, Kankakee, LaSalle, DeKalb, and Rockford. Area code 815 was overlaid with area code 779 in 2007. *847/224: North and northwest suburbs of Chicago including all of Lake County, part of McHenry County, northern Cook County, and northeastern Kane County. This area includes Evanston, Des Plaines, Waukegan, and most of Elgin. Area code 847 was overlaid with area code 224 in 2002. *872: City of Chicago, overlaying area codes 312 and 773. ==History== In the original North American Numbering Plan of 1947, all of the Chicago area was covered by area code 312, the rest of northern Illinois was 815, central Illinois was 217, and southern Illinois was 618. In 1966, area code 309 was split off to cover western central Illinois (which was previously the southwestern part of area code 815). In 1990, area code 708 was split off to cover all of the suburbs in the Chicago metropolitan area (which is now covered by 847/224, 630/331, and 708) while the city of Chicago kept the original 312. Area codes 847 (north suburbs) and 630 (west suburbs) were split off from the suburban area code 708 in 1996. Shortly after in 1996, area code 773 was created as an area code split to cover the residential parts of the city of Chicago while downtown kept the original 312 area code. Area code 847 almost immediately exhausted its numbers, so an overlay area code, 224, was implemented in 1996 for supplemental numbers. However, mandatory 11-digit dialing was not in effect until 2002. In March 2007, the overlay area code 331 was added for 630 area, as was the overlay area code 779 for 815. With the depletion of new numbers in area codes 312 and 773, an overlay of both of them, area code 872, was created in November 2009, beginning 11-digit dialing within the city limits of Chicago. Area code 464 has been reserved for an overlay for 708, but has not been implemented and no timeline exists. Likewise, area code 447 has been reserved for an overlay of 217 and area code 730 reserved for an overlay of 618 in the near future, but no timelines exist. There are no immediate plans for relief for area code 309. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「List of Illinois area codes」の詳細全文を読む スポンサード リンク
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