Cities in area code 840
840 numbers are anchored to 19 rate centers across California. Each row shows how many active prefixes the locality holds — a direct measure of its numbering footprint.
By numbering footprint the leading localities are Pomona, Arrowhead, Fontana, San Bernardino, Chino, Claremont, Ontario and Colton, and 10 smaller communities down to single-prefix localities. Prefix counts track lines in service, so the ranking is a reasonable proxy for where the code's subscribers actually are.
Metropolitan coverage: 19 rate centers belong to FCC top-100 metro areas.
Overlap note: 19 localities are shared with other area codes, so a neighbor's number may differ in its first three digits.
Clock-wise the coverage is Pacific.
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 |
|---|---|---|---|
| Pomona | 16 | Los Angeles-Long Beach-Anaheim, CA | 840, 909 |
| Arrowhead | 14 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Fontana | 12 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| San Bernardino | 11 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Chino | 8 | Los Angeles-Long Beach-Anaheim, CA | 840, 909 |
| Claremont | 7 | Los Angeles-Long Beach-Anaheim, CA | 840, 909 |
| Ontario | 7 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Colton | 6 | Riverside-San Bernardino-Ontario, CA | 840, 909, 951 |
| Upland | 6 | Los Angeles-Long Beach-Anaheim, CA | 840, 909 |
| Redlands | 5 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Marshall | 5 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Highland | 5 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Rialto | 5 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Calimesa | 3 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Diamond Bar | 3 | Los Angeles-Long Beach-Anaheim, CA | 840, 909 |
| Etiwanda | 2 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Mentone | 2 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Big Bear City | 1 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
| Crestline | 1 | Riverside-San Bernardino-Ontario, CA | 840, 909 |
FAQ
What is the biggest city in area code 840?
Pomona holds the most active prefixes (16), making it the code's largest numbering locality.
How many places does 840 cover?
19 rate centers in California hold active 840 prefixes, from Pomona down to communities with a single prefix.
Does a 840 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.