State: Illinois
Major city: Chicago
Time zone: Central
Current time:

History of 312 area code

Area code 312 is a telephone area code for the state of Illinois. It serves downtown Chicago plus the Chicago loop and it surrounding areas. This area code is totally encircled by area code 773, which covers the rest of Chicago. 312 and 773 are both overlays of area code 872. It is one of the smallest area codes serving only a few square miles.

312 was allocated to one of the original area codes that were established in 1947 for the North American numbering plan. The area code was split between four area codes due to the growth of Illinois population in the northern part. After five years, the area code threaten to get exhausted again in the 1990s this resulted in area code 708 splitting in 1996 several years after it was split from area code 312.

See: Who called me

Top Counties in Area Code 312

Cook

Top cities using the area code 312

Chicago

Most Reported Phone numbers

Perform a reverse phone search in Illinois using the list of reported numbers in area code 312 to find out more about the person who possess the number that phoned you.

312-NXX prefixes and their locations