The U.S. state of Illinois is divided into ten distinct geographic numbering plan areas in the North American Numbering Plan (NANP), which are assigned a total of seventeen area codes.

Lookup area code information for CHICAGO, IL. Get the NPA NXX (area code and prefix) as well as much more data for CHICAGO, IL.

Browse our sites area and region codes by state and city to ensure you have the correct information for your calls. Each states page contains a list of the cities within that state and the numbers of that area.

2 days ago · Find out where 312 area code zone from, which states, counties and cities it covers. Get the most exact information on time zones here

Our area code lookup makes it easy to find area codes in Illinois. Includes area code listings of all Illinois area codes with corresponding cities.

List of all area codes in Chicago, IL. Chicago, IL area code map, list, and phone lookup.

Jan 3, 2026 · Illinois - Area code 312 is currently assigned for use in Illinois since January 01, 1947. View all phone prefixes used in area code 312 or other area codes in Illinois.

1 day ago · Our area code lookup makes it easy to find area codes in Chicago. Includes area code listings of all Chicago area codes with corresponding cities.

Find the local area code for Chicago, Illinois. Our complete calling resource guide instantly gives you the the Chicago area code and local time to help you make your long distance call to Chicago, Illinois.

This was a controversal spilt where everyone in the City of Chicago changed their area code except "Chicago Zone 01" - an area that covers the loop. This allowed major corporations based in …