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.

Jan 1, 2026 · 312 Area Code located in Illinois, including 16 cities, 3 counties, 1 time zone, map, Census demographics, and 778 active prefixes.

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.

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.

1 day ago · 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. …

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

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.

312 area code information for Chicago, Illinois. Timezone, overlay codes, and more.

List of ZIP Codes in Area Code 312 ... List of Counties in Area Code 312 Cook County