Chicago, Illinois

Where Is Area Code 312?

Area code 312 is in northeastern Illinois. It serves the central part of the City of Chicago, mainly the downtown area and nearby neighborhoods. It is one of the main area codes associated with Chicago.

Area code 312 is located in Cook County. It covers the Chicago Loop and parts of central Chicago rather than the full metro area. Chicago landmarks in the 312 area include the Loop, the Willis Tower, Millennium Park, and parts of the Magnificent Mile.

Area code 312 is part of Chicago’s core business and civic center. The area includes major office districts, government buildings, transit hubs, and dense residential neighborhoods close to downtown. It sits along Lake Michigan in the city’s central lakefront area.

History of Area Code 312

Area code 312 is one of the original North American area codes created in 1947. It originally covered a much larger part of the Chicago area, and at first it served most of the city and many nearby suburbs. As telephone demand grew, the 312 region became smaller through later area code changes.

In 1989, area code 708 split from 312 and took many suburban areas. In 1996, area code 773 split from 312 and took most of the rest of Chicago outside the downtown core. In 2009, area code 872 began overlay service in the same Chicago areas served by 312 and 773, which made 10-digit dialing necessary.

Key Facts About Area Code 312

• Area code 312 serves Chicago, Illinois, especially the city’s downtown core and nearby central neighborhoods.
• Area code 312 is in the Central Time Zone and follows Central Standard Time and Central Daylight Time.
• Area code 312 is an original area code from 1947 under the North American Numbering Plan.
• Area code 312 is now one of Chicago’s smaller geographic area codes because of the 708 split in 1989 and the 773 split in 1996.
• Area code 312 is overlaid by area code 872, which entered service in 2009 in the same Chicago numbering area.
• Area code 312 is in Cook County, Illinois, which includes the City of Chicago.
• Landmarks associated with the 312 area include the Chicago Loop, Willis Tower, Millennium Park, and the downtown lakefront.
• Major institutions in the 312 area include city and county government offices, the Chicago Board of Trade area, and central business districts in downtown Chicago.

Frequently Asked Questions

What state is area code 312 in?

Area code 312 is in Illinois.

What major cities use area code 312?

Area code 312 is primarily used in Chicago.

Is area code 312 a toll-free number?

No. Area code 312 is a geographic area code for Chicago, Illinois.