Area Code 312

Area Code 312 is in Illinois

Other Illinois Area Codes
217, 224, 309, 312, 331, 447, 464, 618, 630, 708, 730, 773, 779, 815, 847, 861, 872

Illinois Area Code Overlays
(217 and 447) - (224 and 847)
(309 and 861) - (312 and 872)
(331 and 630) - (464 and 708)
(618 and 730) - (773 and 872)
(779 and 815)

Area Code 312 History:

01/01/1947
Area code 312 was officially put into service. In 1989 Area code 312 was split to form area code 708. In 1996 area code 312 was split again to form area code 773. In 2009 area code 312 was overlaid with area code 872.

Counties in Illinois within area code 312 include:

Cook County.

Major cities or places in Illinois within area code 312 include:

Chicago originally utilized area code 312 which was one of the original area codes assigned to Illinois in 1947. In 1996 area code 312 was split to form area code 773. Area code 312 now serves the downtown area, or inside "The Loop" and area code 773 serves the remainder of the city. On November 7, 2009 area code 872 was officially put into service. Area code 872 is an overlay of of both 312 and 773.

Illinois Area Code Map