Area code 318 is a telephone area code in the North American Numbering Plan (NANP) for the northern and central parts of the U.S. state of Louisiana. The area code was assigned in 1957 in an area code split of area code 504, to a numbering plan area that comprised nearly 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 of the original 318, including Lafayette and Lake Charles, received area code 337.

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. 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 Bay Area 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 no longer was required. The entire San Francisco Bay Area returned to using area code 415.

In 1957, Louisiana's original 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.

Further relief will be required in the near future, as 318 is expected to exhaust by early 2026.^[1] An overlay complex (the first in Louisiana) will be created with area code 457 and will take effect beginning September 25, 2025.^[2] A transition to ten-digit dialing will be undertaken ahead of the overlay.

• List of Louisiana area codes
• List of North American Numbering Plan area codes

• NANPA area code map of Louisiana

32°06′N 92°30′W / 32.1°N 92.5°W / 32.1; -92.5