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.

About area code 312: location, common spam callers, related area codes, and more. Includes 312 reverse phone lookup to identify spam callers.

Browse area code 312 phone numbers, prefixes and exchanges. The 312 area code serves Chicago, Willowbrook, Elgin, Arlington Heights, Naperville, covering 23 ZIP codes in 4 counties.

Dec 1, 2025 · 312 Area Code located in Illinois, including 16 cities, 3 counties, 1 time zone, map, Census demographics, and 778 active prefixes.

Mar 9, 2025 · 312 is an area code located in the state of Illinois, US. The largest city it serves is Chicago. Find out where 312 area code zone from, which states, counties and cities it covers. …

Dec 1, 2025 · Rated at No. 6: Area code 312 in Chicago Chicago’s original 312 area code was introduced in 1947 and later confined to the city’s downtown core after the 1989 split that …

Area code 312 is located in Illinois. Get the area’s map, cities covered, current time, prefixes, and dialing instructions.

Find 312 area code details including city, time zone, and map. Lookup area code 312 phone number, name, and location.

Area code 312 is located in Illinois and includes Chicago. View the 312 area code map, major cities, location, timezone and more on TeraCodes.com.

Nov 22, 2025 · Area code 312 is in Illinois, USA. Locate phone numbers 312-200-XXXX through 312-999-XXXX. City list with local time, map and overlaying areas.