Area code 312

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Area code 312 encompasses the Chicago Loop and surrounding areas in Chicago, Illinois. It is roughly bounded by Armitage Avenue on the north, Western Avenue on the west, and 35th Street on the south.

[edit] History

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.

Up until 1989, it included most of Chicagoland, 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.