North American Numbers Source-cited · ownership disclosed
Area code
313
In service
United States · since 1947

Detroit

Detroit and its immediate inner-ring suburbs in Wayne County; one of the original 1947 area codes and the numbering trunk from which all of southeastern Michigan's codes eventually split.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
Detroit
Type
geographic
Status
in service
In service since
1947
Projected exhaust
2091 Q2

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 313 is

Central and eastern Wayne County (city of Detroit and adjacent suburbs)..

Communities served wholly or partly by 313:

DetroitDearbornDearborn HeightsHamtramckHighland ParkGrosse PointeHarper WoodsRedfordLincoln ParkTaylorInksterAllen ParkEcorseRiver RougeMelvindale

Now confined to Detroit and nearby Wayne County suburbs after the 810 (1993) and 734 (1997) splits.

B · Relationships

How it relates to other codes

The codes 313 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Overlay · 2025 679 Detroit (overlay) All-services overlay of the same 313 geography; live Nov 7, 2025.
Spawned · 1993 810 Flint / The Thumb Northern suburbs, Flint and southern Thumb split off from 313.
Spawned · 1997 734 Ann Arbor / western Wayne Western/southern Wayne, Ann Arbor and Monroe split off from 313.
Related 248 Oakland County Oakland County to the north (via 810 lineage).
Related 586 Macomb County Macomb County to the northeast.
What's changing. Overlaid by 679 since Nov 7, 2025; 10-digit dialing mandatory.
C · History

How 313 got here

1947-10
Assigned as one of the original 86 North American area codes; originally covered Metro Detroit, Flint and The Thumb.
Source: Wikipedia
1993-12-01
Area code 810 split off the northern suburbs, Flint and southern Thumb.
Source: Wikipedia
1997-12-13
Area code 734 split off the western portion (Ann Arbor, Monroe, western/southern Wayne).
Source: Wikipedia
2025-10-07
Ten-digit dialing became mandatory (permissive period Apr 7-Oct 7, 2025) ahead of the 679 overlay.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
782
Prefixes available
18
Thousands-blocks assigned
3,449

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 313 with another code →
Sources
Wikipedia ↗
Area codes 313 and 679
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.