List of Illinois area codes

The Chicago metropolitan area, also colloquially referred to as Chicagoland, is the metropolitan area containing the City of Chicago, which includes its surrounding suburbs and satellite cities. Encompassing 10,286 square mi (28,120 km²), the metropolitan area includes the city of Chicago, its suburbs and hinterland, that span 14 counties across northeast Illinois, northwest Indiana, and southeast Wisconsin. The MSA had a 2020 census population of 9,618,502 and the combined statistical area which spans up to 19 counties had a population of nearly 10 million people. The Chicago area is the fifth largest metropolitan area in North America, the fourth-largest metropolitan area in the United States, the largest within the entire Midwest, and the largest in the Great Lakes megalopolis. Its urban area is one of the forty largest in the world.

Area code 312 is a telephone area code in the North American Numbering Plan for the city of Chicago, including downtown, the Chicago Loop, and its immediate environs. The numbering plan area is completely surrounded by area code 773, which serves the rest of Chicago. Both area codes form an overlay complex with area code 872. 312 is an enclave area code, and is roughly bounded by North Avenue on the north, Western Avenue on the west, and 35th Street on the south, with Lake Michigan to the east. In terms of geographic area covered, 312 is one of the smallest area codes in the nation, encompassing only a few square miles.

Area codes 630 and 331 are telephone area codes in the North American Numbering Plan (NANP) for portions of Chicago's near and far western suburbs, including the majority of DuPage County, Illinois. To the northwest, the numbering plan area (NPA) also includes a small portion of Cook County, including parts of Schaumburg, Streamwood and Hanover Park. To the west, Kane County is divided between area codes 847 and 224 in the north, including Elgin, and area codes 630 and 331 in the south, including Aurora. To the south, the northern part of Will County and a small part of southern Cook County, including the village of Burr Ridge and parts of the village of Lemont, are also included in the 630 and 331 area codes. To the southwest, the city of Yorkville, in exurban Kendall County, is included, as well.

Area codes 708 and 464 are telephone area codes in the North American Numbering Plan (NANP) for the southern and western suburbs of Chicago in the U.S. state of Illinois. The numbering plan area comprises most of western and southern Cook County, and eastern and southern Will County.

Area code 781 and 339 are telephone area codes in the North American Numbering Plan for the U.S. state of Massachusetts. The numbering plan area consists of Boston’s inner suburbs, known as the Route 128 corridor, and some outer suburbs, especially in the South Shore region. It was created as in an area code split of area code 617 on September 1, 1997. Use of 781 became mandatory February 1, 1998. Area code 339 is an overlay complex code for the same service area, activated on May 2, 2001. Since then, ten-digit dialing is mandatory.

Area codes 847 and 224 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. state of Illinois. The numbering plan area (NPA) comprises the northeastern part of Illinois and many northern suburbs of Chicago. This includes most of Lake County, the northern part of Cook County, the northern part of Kane County, and a small part of McHenry County.

Area codes 208 and 986 are telephone area codes in the North American Numbering Plan for all of Idaho. Area code 208 is one of the 86 original area codes created by the American Telephone and Telegraph Company in 1947. It was Idaho's sole area code until 2017, when 986 was added as a second area code to the same numbering plan area by creating an overlay complex.

Area code 403 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Alberta. The numbering plan area encompasses the southern third of the province, which includes the Calgary area. This numbering plan area is also served by area codes 587, 825, and 368, which form a complex overlay for all of Alberta.

Area code 780 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Alberta. The numbering plan area comprises the northern two thirds of the province, including the Edmonton area. The area code was established in 1999 in a split of area code 403, which had served the entire province since the establishment of the original North American area codes in 1947. The numbering plan area is also served by area codes 587, 825, and 368, which form a complex overlay for all of Alberta.

Area code 604 is a telephone area code in the North American Numbering Plan for southwestern British Columbia, Canada. The numbering plan area comprises the Lower Mainland, Sunshine Coast, Howe Sound / Sea to Sky Corridor, Fraser Valley and the lower Fraser Canyon regions. The major city is Vancouver. The area code is one of the nine original North American area codes assigned to Canada in 1947.

Area codes 217 and 447 are telephone area codes in the North American Numbering Plan (NANP) for much of the central part of the U.S. state of Illinois. The numbering plan area (NPA) includes the state capital, Springfield, and Champaign, Urbana, Decatur, Taylorville, Lincoln, Danville, Effingham, Quincy, Rantoul, and Jacksonville. 217 was one of the original North American area codes created in 1947 and 447 was added to the same area in 2021 to form an all-services overlay.

Area codes 309 and 861 are telephone area codes in the North American Numbering Plan (NANP) for the west-central part of the U.S. state of Illinois. The numbering plan area includes cities such as Bloomington, Canton, East Moline, East Peoria, Galesburg, Geneseo, Kewanee, Macomb, Minonk, Moline, Morton, Normal, Pekin, Peoria, Rock Island, Silvis, and many smaller communities in west-central Illinois. Area code 309 was created in 1957 in an split of area code 815. 861 was added to the numbering plan area on February 24, 2023, in formation of an overlay.

Area codes 815 and 779 are telephone area codes in the North American Numbering Plan (NANP) for most of northern Illinois outside the Chicago and Quad Cities areas. It also serves the Joliet area and some of Chicago’s western and northwestern exurbs. 815 was one of the four original Illinois area codes set up in 1947. Area code 779 was assigned to the same numbering plan area in 2009 to form an overlay.

Area codes 587, 825, and 368 are telephone area codes in the North American Numbering Plan (NANP) for the entire Canadian province of Alberta. They form an overlay with area code 403 of southern Alberta, and northern Alberta's 780. The complex overlay involving a total of five area codes in Alberta mandated ten-digit dialing throughout the province.

Area code 872 is a telephone area code in the North American Numbering Plan for Chicago in the U.S. state of Illinois. It is an overlay code for a numbering plan area that comprises those of area codes 312 and 773. The overlay commenced service on November 7, 2009. Its overlay status means it is assigned only to new numbers in the area and not to existing numbers using the 312 and 773 area codes. It is the third overlay area code in the region and the tenth area code to serve northeast Illinois.

Area code 773 serves Chicago, Illinois, outside the Loop and the innermost neighborhoods.