Cities in area code 312
Area code 312 serves 8 localities in Illinois, led by Chicago Zone 01, Wheeling, Hinsdale. The table lists every rate center — the billing locality each prefix is anchored to — with its share of the code's 785 active prefixes.
By numbering footprint the leading localities are Chicago Zone 01, Wheeling, Hinsdale, La Grange, Northbrook, Roselle, Chicago Zone 07 and Chicago Zone 04. Prefix counts track lines in service, so the ranking is a reasonable proxy for where the code's subscribers actually are.
Metropolitan coverage: 8 rate centers belong to FCC top-100 metro areas.
Overlap note: 8 localities are shared with other area codes, so a neighbor's number may differ in its first three digits.
Clock-wise the coverage is Central.
A caller's real location can differ: numbers port between carriers and follow their owners when they move. Use the prefix tables to see where a specific number block was issued.
| Locality (rate center) | Active prefixes | Metro area | All codes serving it |
|---|---|---|---|
| Chicago Zone 01 | 747 | Chicago-Naperville-Elgin, IL-IN | 312, 630, 708, 773, 847, 872 |
| Wheeling | 12 | Chicago-Naperville-Elgin, IL-IN | 224, 312, 630, 708, 847 |
| Hinsdale | 11 | Chicago-Naperville-Elgin, IL-IN | 312, 331, 630, 708, 847 |
| La Grange | 8 | Chicago-Naperville-Elgin, IL-IN | 312, 464, 630, 708, 815, 847 |
| Northbrook | 3 | Chicago-Naperville-Elgin, IL-IN | 224, 312, 630, 708, 815, 847 |
| Roselle | 2 | Chicago-Naperville-Elgin, IL-IN | 224, 312, 331, 630, 708, 847 |
| Chicago Zone 07 | 1 | Chicago-Naperville-Elgin, IL-IN | 312, 773, 872 |
| Chicago Zone 04 | 1 | Chicago-Naperville-Elgin, IL-IN | 312, 773, 872 |
FAQ
What is the biggest city in area code 312?
Chicago Zone 01 holds the most active prefixes (747), making it the code's largest numbering locality.
How many places does 312 cover?
8 rate centers in Illinois hold active 312 prefixes, from Chicago Zone 01 down to communities with a single prefix.
Does a 312 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.