Cities in area code 331
Which places use area code 331? 24 rate centers in Illinois, the biggest being Aurora, Naperville, Downers Grove. Data below is NANPA's official prefix-to-rate-center mapping.
Aurora, Naperville, Downers Grove, Saint Charles, Lombard, Elmhurst, Lemont and Bartlett hold the largest prefix inventories; and 15 smaller communities down to single-prefix localities. Each locality below links to its rate-center page with the full prefix list.
24 of the localities fall within FCC top-100 metropolitan statistical areas; the rest are smaller communities.
24 of these localities are also reachable through other area codes — overlay territory where the same place answers to several codes.
All of the code's territory keeps Central time.
Remember that people keep numbers when they relocate, so a 331 number is a where-it-was-issued fact, not a where-they-are fact.
| Locality (rate center) | Active prefixes | Metro area | All codes serving it |
|---|---|---|---|
| Aurora | 45 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Naperville | 32 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Downers Grove | 21 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Saint Charles | 17 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Lombard | 13 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Elmhurst | 10 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Lemont | 10 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Bartlett | 8 | Chicago-Naperville-Elgin, IL-IN | 224, 331, 630, 847 |
| West Chicago | 8 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Oswego | 7 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Wheaton | 7 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Geneva | 7 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Sugar Grove | 6 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Hinsdale | 6 | Chicago-Naperville-Elgin, IL-IN | 312, 331, 630, 708, 847 |
| Yorkville | 4 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Itasca | 3 | Chicago-Naperville-Elgin, IL-IN | 331, 630, 847 |
| Elburn | 3 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Glen Ellyn | 3 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Warrenville | 2 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Batavia | 2 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Big Rock | 2 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Plano | 2 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Kaneville | 2 | Chicago-Naperville-Elgin, IL-IN | 331, 630 |
| Roselle | 1 | Chicago-Naperville-Elgin, IL-IN | 224, 312, 331, 630, 708, 847 |
FAQ
What is the biggest city in area code 331?
Aurora holds the most active prefixes (45), making it the code's largest numbering locality.
How many places does 331 cover?
24 rate centers in Illinois hold active 331 prefixes, from Aurora down to communities with a single prefix.
Does a 331 number guarantee the caller lives in one of these places?
No — the tables show where number blocks were issued. Porting and VoIP let people keep or acquire numbers anywhere.