North American Numbers Source-cited · ownership disclosed
Area code
951
In service
United States · since 2004

Riverside

Area code 951 serves western Riverside County, California, including the city of Riverside. It was created on July 17, 2004 by a split of area code 909 and was the last traditional geographic split in California.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
Riverside
Type
geographic
Status
in service
In service since
2004
Projected exhaust
2031 Q4

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 951 is

Western Riverside County, California, with small portions of San Bernardino County (Colton, Grand Terrace)..

Communities served wholly or partly by 951:

RiversideCoronaTemeculaMurrietaHemetMoreno ValleyLake ElsinorePerrisMenifee

Representative list of principal communities, not exhaustive.

B · Relationships

How it relates to other codes

The codes 951 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Split from · 2004 909 Inland Empire (San Bernardino) 951 was assigned to the southern portion of 909 in a two-way geographic split.
What's changing. No overlay; created by geographic split. Ten-digit dialing mandatory since October 24, 2021 (988 transition).
C · History

How 951 got here

2004-07-17
Area code 909 divided in a two-way geographic split, assigning 951 to its southern (western Riverside County) portion; the last traditional split in California.
Source: Wikipedia
2021-10-24
Transitioned to mandatory ten-digit dialing due to the nationwide 988 code.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
709
Prefixes available
91
Thousands-blocks assigned
4,551

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 951 with another code →
Sources
Wikipedia ↗
Area code 951
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.