Once the mother area code of all of southern California
, AC 213 has been reduced to covering a 12 mile radius surrounding the heavily used downtown Los Angeles, California
In 1947, was one of the first A/C's to be used in the NANP (201, for New Jersey, was the first to be issued). As SoCal became more populous, however, it was clear that there were going to be more than seven million phone numbers needed for the region. Thusly it became the mother of many area codes created for use in California.
One of the first splits was 805, created in 1957 for Ventura County on north to San Luis Obispo, as well as north LA County and areas up to Bakersfield, California. 714 split off of this later on as well, in the early 1960s. All was quiet until 1984, when 818 was created to cover the San Gabriel and San Fernando valleys; later, in 1991, 310 was created to cover western, eastern, and southern LA County.
In 1995, the restriction that dictated that area codes must use a 0 or 1 as their central digit was lifted, making a plethora of new possible area codes available; out of this was created 562 for the eastern half of 310 in January 1997, 626 for everything east of Pasadena in what was 818 in June of 1997, and 323 for the remainder of the 213 area except as described above.
Currently proposed is an overlay for 424, over the West LA area of 310; this is the subject of much contention, however, as in some cases this would require somebody to dial an area code for their roommate or next door neighbor (or rather, moreso than a typical area code split).