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 created in 1957 in a split of Louisiana's original area code 504. Originally, it covered 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, became area code 337.