Area codes 630 and 331
Area codes 630 and 331 under the North American Numbering Plan in the United States, cover portions of Chicago's near and far western suburbs, including the majority of DuPage County, Illinois. To the northwest, the area codes also cover a small, neighboring portion of Cook County, including parts of Schaumburg, Streamwood and Hanover Park. To the west, Kane County is divided between area codes 847 and 224 in the north, including Elgin, and area codes 630 and 331 in the south, including Aurora. To the south, the northern part of Will County and a small part of southern Cook County, including the village of Burr Ridge and parts of the village of Lemont, are also included in the 630 and 331 area codes. To the southwest, the city of Yorkville, in exurban Kendall County, is included, as well.
The main area code, 630 was split off from area code 708 on August 3, 1996. Within a decade, 630 was close to exhaustion due to the explosive growth of the Chicago suburbs and the proliferation of cell phones and pagers. On October 7, 2007, area code 331 began overlaying area code 630, making ten-digit dialing mandatory in the area.Communities included
