About Illinois Area Code 312

The 312 area code includes Illinois city Chicago.

Nearby area codes are 219, 224, 331, 630, 708, 773, 847 and 872.
Search for a phone number:
Example: 312-555-5555

Extended information

Area code 312 encompasses the Chicago Loop and surrounding areas in Chicago, Illinois. It is roughly bounded by North Avenue on the north, Western Avenue on the west, Lake Michigan on the east, and 31st Street on the south. By size, it is one of the smallest area codes in the nation encompassing only a few square miles.

312 was one of the original 86 area codes created in 1947, then called "Numbering Plan Areas." With the rotary dialing technology available at the time, care was given to keep the number of "clicks" to a minimum for large cities, hence Chicago being assigned a code with only six clicks. The first production #4ESS toll switch was installed in January 1976.

Until 1989, 312 included most of the Chicago metropolitan area; at that time the suburbs became area code 708. In 1996, most of the city split off into 773 after the northern suburbs and western suburbs split into area codes 847 and 630 respectively, while the southern and western suburbs kept 708.

When 312 covered the entire city, city residents would derisively call suburbanites "708-ers" in reference to their area code.

312 Area Code Exchanges 100-153:

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