This pack follows a core family of Los Angeles County area codes descended from the original 213 code. Understanding them means understanding how those codes split apart and later overlapped — not just listing them.
How Los Angeles's Original Area Code Split Into Today's Core Codes
When the first North American Numbering Plan was drawn up in 1947, a single area code — 213 — served a broad Southern California territory. As demand grew, the supply of central-office codes ran short, and successive relief plans split 213 into new codes and later overlaid still more on top of them. This pack traces that lineage for the core Los Angeles County codes.
Scope. This is the 213 lineage for the core Los Angeles County codes — the 213 → 818 / 310 / 323 branches and their overlays. It is not a list of every area code in Greater Los Angeles (which by some definitions also includes 661, 562, 714/949, 909/951, 805 and others), nor a complete tree of every code ever derived from 213.
Area code genealogy
Illustrative relationships, not a geographic map. → split = a new code was carved out of the one on the left, and those numbers changed. ⇢ overlay = a new code was layered over the same area, and no existing number changed.
◈ Overlay complex (2017): 213 + 323 — In 2017 the boundary between 213 and 323 was removed: they became a mutual all-services overlay, so either code can be assigned anywhere in the combined region. 738 was later overlaid on top of this complex.
Timeline
1947 · 213
213 was one of the original North American area codes, serving a broad Southern California territory.
Source: CPUC 213 Report (primary)
1984 · 818
The 213 area was geographically split and 818 was implemented, taking the San Fernando and San Gabriel Valleys.
Source: CPUC 818 Report (primary)
1991 · 310
310 was created by a geographic split from 213, covering the Westside, South Bay and coastal L.A. County.
Source: CPUC 310 Report (primary)
1997 (Jan) · 562
562 was split from 310, serving Long Beach and the southeast L.A. County corridor.
Source: CPUC 310 final decision (primary)
1997 (Jun) · 626
The 818 area was geographically split and 626 was implemented, taking the eastern San Gabriel Valley.
Source: CPUC 818 Report (primary)
1998 (Jun) · 323
323 was split from 213; 213 kept downtown exchanges while 323 took surrounding areas such as Hollywood. (An earlier "1997" figure refers to the 1997 CPUC decision, not the in-service split.)
Source: CPUC news release, June 13 2017 (primary)
2006-07-26 → 08-26 · 424
424 was added as an all-services overlay of 310 — California's first overlay. Mandatory 1+10-digit dialing began July 26, 2006; new 424 numbers became assignable August 26, 2006 (CPUC Decision D.05-08-040).
Source: CPUC news release 58447 (primary)
2009 · 747
747 was added as an all-services overlay of the 818 area, approved by CPUC decision on April 24, 2008 and in service in 2009.
The boundary between 213 and 323 was eliminated, converting them into a mutual all-services overlay complex (each code can be assigned across the combined region). CPUC ordered this in July 2016; mandatory 10-digit dialing took effect July 8, 2017.
Source: CPUC news release, June 13 2017 (primary)
2024-11-01 · 738
738 went into service as an additional all-services overlay on the combined 213/323 region (CPUC decision March 16, 2023).
Source: CPUC 213/323/738 page (primary)
Cite & reuse
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North American Numbers, “How Los Angeles's Original Area Code Split Into Today's Core Codes,” data pack v2026.2, last updated 2026-09-18. https://northamericannumbers.org/metro/los-angeles
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The timeline and genealogy as structured data (CC BY 4.0 — attribute NorthAmericanNumbers.org).
213/323/738 Area Codes page — 738 overlay, decision March 16 2023, in service Nov 1 2024
The 1947 origin, the split-vs-overlay type of every event, and the recent overlay dates (424, 747, the 2017 213/323 boundary elimination, and 738) are confirmed by primary CPUC documents (reports, decisions and news releases). For the 1980s–1990s splits, CPUC records confirm the year — and in some cases the month — and that each was a geographic split; documents from that era do not preserve an exact calendar day, so we show the CPUC-confirmed year or month rather than a precise day we cannot source to a primary record.
Changelog: v2026.2 — corrected 424 dates (mandatory dialing vs in-service), rebuilt genealogy with split/overlay edge types and the 213/323 overlay complex, promoted split/overlay types and years to primary CPUC sources.