Locations for Area Code - 331

Area code 331 is an overlay of 630 and serves the western suburbs of Chicago, including Naperville, Aurora, Wheaton, and Oak Brook. Introduced in 2007, it was created to accommodate growing demand in the collar counties of DuPage and western Cook. The region blends suburban affluence with commercial and retail centers, as well as a strong tech and corporate presence. Ten-digit dialing is required throughout the area. While newer and less culturally established than 630, area code 331 represents suburban expansion and digital-era growth in one of the nation’s largest metro regions.