The 331 Area Code was first put into service on October 7, 2007. It was an overlay for 630 area codes and served the same area.
The 331 Area Code is located in Illinois. The code covers Aurora, Naperville, Bolingbrook and surrounding areas. It is also an overlay for area code 630.
Illinois Counties within Area Code 331:
DuPage, Kane, Kendall, Will.
Illinois Major Cities within Area Code 331:
Aurora, Naperville, Bolingbrook, Wheaton, Downers Grove, Elmhurst, Lombard, Carol Stream, Bartlett, Streamwood, Hanover Park, Addison, Glendale Heights, St. Charles, Woodridge, Oswego, Glen Ellyn, West Chicago, Batavia, Westmont, Roselle, Lisle, Darien, Bloomingdale, Villa Park, Geneva, Montgomery, Bensenville, North Aurora, Hinsdale, Yorkville, Lemont, Wood Dale, Warrenville, Plano, Burr Ridge, Campton Hills, Winfield, Sugar Grove, Itasca, Willowbrook, Clarendon Hills, Joliet, Boulder Hill, Plainfield, Oak Brook, Elburn, Romeoville, Wayne, Oakbrook Terrace.
Area Code 217 Time Zone?
Central time zone is also known as America/Chicago.