Area code 312

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Area code 312 is the telephone area code for downtown Chicago, which includes the Chicago Loop and its immediate environs. The plan area is completely surrounded by area code 773, which serves the rest of Chicago, along with overlay area code 872. 312 is an enclave area code, similar to area code 213 in Los Angeles, area code 514 in Montreal, area code 210 in San Antonio and area code 316 in Wichita, Kansas. It is roughly bounded by North Avenue on the north, Ashland Avenue on the west, and 31st Street on the south, with Lake Michigan to the east. In terms of geographic area covered, 312 is one of the smallest area codes in the nation, encompassing only a few square miles.


Area code 312 was one of the original 86 number plan areas (NPAs) created in 1947 for the North American Numbering Plan. Given the rotary dial technology available at the time, AT&T kept the number of pulses to a minimum for the largest cities. Chicago was assigned a code with only six clicks, tied with 213 for the second-fastest that could be dialed under the original guidelines, after area code 212 assigned to New York City. The digits 0 and 1 were not allowed as the first digit, the second digit was either 0 or 1, and the third digit could not be the same as the second digit.

Area code 312 originally served almost all of the Illinois side of the Chicago metropolitan area, except for portions of Grundy, McHenry, and Will counties in the area code for the rest of northern Illinois, 815. On November 11, 1989, the suburban portion split off as area code 708, with 312 reduced to Chicago.

Within only five years, 312 was on the verge of exhaustion once again due to the proliferation of cell phones, pagers and fax machines. As a solution, area code 773 was assigned for the remainder of the city outside of the downtown area on October 11, 1996, making Chicago one of the few cities in the nation to be split between multiple area codes (along with New York City and Los Angeles). Since November 7, 2009, both 312 and 773 have been overlaid by 872.

The first production #4ESS toll switch was installed in Chicago in January 1976.[1][clarification needed]

In popular culture[edit]

  • Goose Island Brewery brews an ale named "312 Urban Wheat Ale" and "312 Urban Pale Ale".[2]
  • A restaurant at the Kimpton Hotels operated Hotel Allegro, at LaSalle and Randolph Streets in the Loop, is named "312 Chicago".[3]
  • The Chicago-based Christian rock group Resurrection Band released a song called "Area 312" on their 1982 album D.M.Z.[4]
  • Portions of the film RoboCop 2 were filmed in the Chicago area. A telephone number written on an abandoned building is (312) 555-7890.
  • The Snoop Dogg song "That's That", contains the lyrics: "Girl if you ever in the 312, holla at a playa".
  • The music project Radio Flyer used (312) as a track title.
  • The Kanye West song "New God Flow," contains the lyrics: "What has the world come to, I'm from the 312, where cops don't come through, and dreams don't come true."
  • The Disney Channel[5] show Shake It Up, starring Bella Thorne,[6] as Cecelia Grace "CeCe"[7] Jones, and Zendaya,[8] as Raquel "Rocky"[9] Oprah Blue, mentions 312 as both Rocky and Cece's area code.

See also[edit]


  1. ^ Telephone World
  2. ^ "312 Urban Wheat". Goose Island Brewery. 2009. Retrieved 19 August 2009. 
  3. ^ "Dining-Hotel Allegro". Hotel Allegro. 2009. Retrieved 19 August 2009. 
  4. ^ Area 312 at AllMusic
  5. ^ Disney Channel
  6. ^ Bella Thorne
  7. ^ Rocky Blue#CeCe Jones
  8. ^ [1]
  9. ^ Blue

External links[edit]

Illinois area codes: 217, 224, 309, 312, 331, 618, 630, 708, 773, 779, 815, 847, 872
North: 773
West: 773 area code 312 (overlaid by 872) East: Lake Michigan
South: 773

Coordinates: 41°52′48″N 87°37′54″W / 41.88°N 87.6316667°W / 41.88; -87.6316667