415 was one of the original three area codes in California, established in 1947. It originally covered central California, south of area code 916 and north of area code 213. In 1950 its boundaries were realigned: area code 916 was reduced to the north-eastern corner of California, while 415 was extended along the north coast to the Oregon border.
Since its creation the 415 area code has had four additional area codes added:
- On August 2, 1997, area code 650 was created; the partition approximately followed the boundary between San Francisco, which (along with Marin County) kept 415, and San Mateo County to the south, which received the new code. Deviations from the county line were a very small area east of the San Francisco Golf Club, which was changed to 650, and portions of Brisbane and Daly City, which retained area code 415.
In December 1998, with the entry of new telephone companies into the market, the number of available prefixes was low enough that the North American Numbering Plan Administrator petitioned the CPUC for a new area code. The CPUC acted April 1, 1999 ordering the overlay of 628 on the existing 415 area code. 1998 there was significant concern expressed by the legislature and the public about the proliferation of new area codes. Because of public concern, the CPUC pursued methods of conserving prefixes. These measures proved to be effective and the CPUC and the FCC implemented number pooling in March 2000 (FCC 00-104). The CPUC suspended its earlier decision to introduce a new area code to the 415. The number conservation measures adopted by the FCC and supported by the CPUC have extended the life of the 415 area code by 14 years.