Area code 313

History

Area code 313 was assigned as one of the original 86 area codes in October 1947. It originally served the southeastern quadrant of Michigan, including Metro Detroit, Flint, and the southern part of The Thumb. The rest of the eastern half of the Lower Peninsula was assigned to area code 517.

Because of the demand for new telephone service in Detroit's suburbs and neighboring areas, the northern portion, including Detroit's northern suburbs, Flint and the southern Thumb were split off with new area code 810 on 1 December 1993 with a permissive dialing period that ended on August 10, 1994. On 13 December 1997, the remaining 313 area was reduced to its current size when the western portion, including Ann Arbor, Monroe County and western and downriver Wayne County, received area code 734 in another split.

Area code 679 has been reserved as a future overlay for the 313 territory. In February 2000, the area code was assigned as a second area code in the county of Wayne in the southeastern part of the U.S. state of Michigan. However, the relief schedule was cancelled in April 2000, and the implementation of the overlay was suspended. Relief planning is in progress, but 2021 estimates do not expect 313 to be exhausted until 2025. Opponents cite the cultural importance and impact of area code 313, in which "313" is often synonymous with the city of Detroit.