Area code 312 is the original area code for Chicago, Illinois, and covers the downtown core—including the Loop, River North, Streeterville, and parts of the Near North Side. Introduced in 1947, it’s one of the most iconic and prestigious area codes in the U.S., often seen as a badge of credibility and legacy. It is now overlaid by 872 but still in use for many longstanding businesses and institutions. Downtown Chicago is the financial, legal, and commercial heart of the Midwest, home to the Chicago Board of Trade, numerous law firms, Fortune 500 companies, and cultural landmarks like Millennium Park and the Art Institute. With world-class dining, architecture, and urban planning, the 312 area projects strength, heritage, and access to influential markets. A 312 number is a powerful signal for any business or professional looking to establish authority and presence in Chicago’s central business district.