The Chicago Split: How 312 Became 773, 708, 847, and More
Chicago started with a single area code in 1947. The city's growth forced repeated splits that turned one code into six. Here's the story of 312 and its successors.
312: Chicago's Original Code
In 1947, area code 312 was assigned to all of Illinois. Chicago, as the dominant population center, drove the number demand, and 312 became synonymous with the city. For nearly four decades, 312 served Chicago and its suburbs together.
The First Split: 618 and 217
As Illinois grew, the state was divided. Southern Illinois received 618 and central Illinois received 217, leaving 312 to serve the northern portion of the state — still a massive territory including Chicago and all its suburbs.
The Suburban Exodus: 708
By 1989, even the northern Illinois territory was struggling. The Chicago suburbs — a sprawling constellation of communities stretching from Lake County in the north to Will County in the south — were split off into area code 708. This left 312 serving the city of Chicago proper.
Suburban Demand Continues: 847 and 630
The suburbs kept growing. In 1996, the northern suburbs (including Evanston, Skokie, and the North Shore communities) received area code 847, splitting from 708. The western suburbs (Naperville, Aurora, Wheaton) received 630 in 1996 as well.
The City Split: 773
Even Chicago itself needed relief. In 1996, area code 773 was created for the Chicago neighborhoods outside of the downtown Loop area. 312 was retained for the downtown business district — the densest concentration of office lines in the city. Today, 312 covers the Loop and near downtown, while 773 covers the rest of the city's neighborhoods.
The Complete Chicago Area Code Picture
Greater Chicago today is served by six active area codes: 312 (downtown), 773 (Chicago neighborhoods), 708 (south/southwest suburbs), 847 (north suburbs), 630 (west suburbs), and 331 (west suburbs overlay). One city, six codes — a testament to how radically telephone demand transformed in just 50 years.
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