Originally, the plan area covered the far northern portion of the state.
In 1950, as part of a realignment of California's area codes, 916 was rotated to cover the northeastern corner of California, from the Sierra Nevada to the Central Valley.
[citation needed] The numbering plan area was split in a flash-cut on March 1, 1959, when area code 707 was created out of the northwest portion.
[1] In 2017, the CPUC approved an overlay area code to take effect in 2018, as all available prefixes were expected to be allocated by December 2018.
[4] Area codes 916 and 279 encompass Sacramento and its surrounding suburbs: