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 and area code 210 in San Antonio. It is roughly bounded by North Avenue on the north, Western Avenue on the west, and 35th 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 Wikipedia
Area code 312 was one of the original 86 number plan areas (NPAs) created in 1947 for the North American Numbering Plan. Due to Illinois' dense population, particularly in the north, it was split between four NPAs, given that each NPA could only accommodate approximately 500 central offices.
Area code 312 originally served almost all of the Illinois side of the Chicago metropolitan area, except for portions of Grundy, Kane, McHenry, and Will counties in the area code for the rest of northern Illinois, 815. On November 11, 1989, the suburbs were assigned area code 708 and 312 was reduced to Chicago.
The 1989 split was intended as a long-term solution to relieve exchanges in one of the largest toll-free calling zones in the nation. However, within only five years, 312 was on the verge of exhaustion once again due to the proliferation of cell phones, pagers and fax machines. Additionally, the Chicago LATA extends for some distance into northwest Indiana (Gary, Hammond, East Chicago), and several numbers in northern Indiana's 219 weren't available for use. As a solution, all of the city outside of the Loop was split off as area code 773 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, making ten-digit dialing mandatory in Chicago.
The first production #4ESS toll switch was installed in Chicago in January 1976.Goose Island Brewery brews an ale named "312 Urban Wheat Ale" and "312 Urban Pale Ale".
A restaurant at the Kimpton Hotels operated Hotel Allegro, at LaSalle and Randolph Streets in the Loop, is named "312 Chicago".
The Chicago-based Christian rock group Resurrection Band released a song called "Area 312" on their 1982 album D.M.Z.
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 Ludacris song Area Codes has 312 as one of the 43 area codes mentioned.
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 show Shake It Up, starring Bella Thorne, as Cecelia Grace "CeCe" Jones, and Zendaya, as Raquel "Rocky" Oprah Blue, mentions 312 as both Rocky and Cece's area code.
A 1960s AT&T commercial promoted calling long distance with the jingle "3-1-2 .. 3-1-2 That toddlin town, that toddlin town", this jingle playing upon "Chicago" a popular song written by Fred Fisher, cleverly taught the nation this Chicago area code.