Area codes 318 and 457 are telephone area codes in the North American Numbering Plan (NANP) for the northern and central parts of the U.S. state of Louisiana. Area code 318 was assigned in 1957 in an area code split of the 504 numbering plan area (NPA) to nearly all of the state west of the Mississippi River, stretching from the Gulf of Mexico north to the border with Arkansas. After reduction of the numbering plan area In 1999, in which the southern half of 318 received area code 337, the numbering plan area was converted in 2025 to an overlay complex with additional area code 457.
During the initial trials of direct distance dialing (DDD) in 1951, area code 318 was temporarily used as a destination code for San Francisco. Oakland and San Francisco had separate toll switches, so that calls had to be routed accordingly depending on the final destination in the Bay Area. As the telephone equipment used at the time handled only three-digit translation, the temporary use of a distinct area code was required to distinguish between the two cities. Area code 318 was used temporarily to specify San Francisco and areas north of the Golden Gate Bridge, while calls with destinations in Oakland or the East Bay used area code 415. When the electromechanical card-translator became available by 1953, translations using six digits were possible; the 318 code was no longer required. The entire San Francisco Bay Area returned to using area code 415.
In 1957, Louisiana's originally sole area code 504 was split to create a numbering plan area with area code 318 for all of the state west of the Mississippi River, stretching from the Gulf of Mexico north to the border with Arkansas.
In 1999, the southern half, including Lafayette and Lake Charles, was split off with area code 337.[1]
Further relief planning began in 2023, as 318 was expected to exhaust by early 2026.[2] The Louisiana Public Service Commission has approved an all-service overlay complex, the first in Louisiana, with area code 457, which is scheduled to be in service on September 25, 2025.[3] A permissive ten-digit dialing period in 318 was in progress from February 24, 2025 to August 25, 2025, after which ten-digit dialing became mandatory.
32°06′N 92°30′W / 32.1°N 92.5°W / 32.1; -92.5
