Area Code 313
Michigan
Area code 313 serves Michigan, primarily Detroit, in the Eastern Time (ET) time zone. It has served the region since 01-Jan-1947.
Overlay Area Codes
This area code is part of an overlay region, meaning the same geographic area is served by multiple area codes. Overlay codes were introduced to meet growing demand for phone numbers without requiring existing customers to change their numbers.
This area code shares its geographic region with: area code 313 (Detroit), area code 679 (Detroit).
In service since: 01-Jan-1947
Area Code Splits
Parts of this area code’s original geographic region were later assigned new area codes through splits. When a split occurs, some customers in the original area code region are assigned the new area code.
Split into: area code 734 (Ann Arbor), area code 810 (Flint).
Demographics & Economics
- Total Population
- 1,080,643
- Population Density
- 2,851 people/sq miabove U.S. average (U.S.: 93 people/sq mi)
- Median Household Income
- $59,521below U.S. median (U.S.: $75,144)
- Poverty Rate
- 19.8%above U.S. average (U.S.: 11.5%)
- Unemployment Rate
- 8.6%above U.S. average (U.S.: 3.6%)
- Education Attainment
- Bachelor's Degree+26.9%below U.S. average (U.S.: 33.7%)High School or Lower33.4%
Statistics are population-weighted aggregations from Census ACS 5-year estimates. Population figures are approximate — see Sources & Methodology for details on how area code populations are derived.
See how this area code compares to all US area codes in the income ranking and density ranking.
Time Zone
- Eastern Time (ET)
NANPA Relief Status
According to the latest NANPA analysis (July 2026), this area code is not currently listed as exhausting within the next 36 months. No relief planning is in progress for this NPA.
Source: NANPA NPA Relief Planning Reports · See all relief planning statuses
Current Time
Prefix Utilization
Geographic Coverage
State
MI
Major Cities
- Detroit
- Dearborn
- Taylor
- Dearborn Heights
- Lincoln Park
- Allen Park
- Hamtramck
- Inkster
- Grosse Pointe Woods
- Harper Woods
- Melvindale
- Grosse Pointe Park
- Grosse Pointe Farms
- Ecorse
- Highland Park
- River Rouge
- Grosse Pointe
- Village of Grosse Pointe Shores
- Redford
Historical Timeline of Area Code 313
Area code 313 was created in October 1947 as one of the original 86 North American area codes, assigned to the entire southeastern quadrant of Michigan including Detroit, Flint, and the southern Thumb. The area code underwent two geographic splits before an overlay with area code 679 was approved in 2001 and finally implemented in November 2025 after a 24-year delay caused by thousands-block number pooling conservation measures. Source: NANPA PL-618
Key milestones:
- 1947: Created as one of the original 86 area codes, assigned to southeastern Michigan including Detroit, Flint, and the southern Thumb. Source: MPSC Case U-21337
- 1993: First split: area code 810 created December 1, 1993 for Oakland, Macomb, Genesee, Lapeer, St. Clair, and Sanilac counties. Permissive dialing continued until August 10, 1994. Area code 810
- 1997: Second split: area code 734 created December 13, 1997 for Ann Arbor, Monroe County, and western/downriver Wayne County, reducing 313 to Detroit and immediate suburbs. Area code 734
- 2000: Area code 679 reserved for overlay (February 2000). NeuStar submitted relief petition to FCC (April 20, 2000). Initial schedule canceled after Public Act 295 of 2000 granted MPSC numbering authority. Source: MPSC Order U-21337
- 2001: MPSC approved all-services distributed overlay introducing 679 NPA for 313/734 (September 7, 2001, Case U-12880). Implementation deferred due to conservation measures. Source: MPSC Order U-12880
- 2002: Thousands-block number pooling began in 313 NPA (February 2002), extending the area code lifespan by over 20 years and delaying 679 implementation. Source: MPSC Case U-21337
- 2022: NANPA filed petition for 679 overlay implementation (November 16, 2022, Case U-21337). 313 projected to exhaust Q3 2025. Source: MPSC Case U-21337
- 2023: MPSC approved 679 overlay (May 18, 2023, Case U-21337). NANPA published PL-618 (July 13, 2023). Public hearing held March 9, 2023 at Wayne County Community College. Source: NANPA PL-618
- 2025: 679 overlay implemented: permissive 10-digit dialing April 7, 2025; mandatory October 7, 2025; 679 CO codes activated November 7, 2025. Source: NANPA PL-618
The 313 area code remains the primary code for Detroit and its immediate suburbs, with area code 679 serving as an overlay for new number assignments once 313 prefixes are exhausted, currently projected for Q4 2027. Area code 679
Regulatory History
Area code 313 has undergone four major regulatory actions spanning 25 years, from the initial legislative framework through overlay implementation. Michigan's numbering authority derives from FCC rule 47 CFR 52.19(2), delegated to the Michigan Public Service Commission under state statute MCL 484.2101 et seq. Source: MPSC Order U-21337
| Year | Event | Docket | Regulatory Action & Impact |
|---|---|---|---|
| 2000 | Legislative authority | PA 295 of 2000 | Michigan Legislature granted MPSC explicit authority over area code numbering, superseding prior FCC-led process. Canceled the April 2000 overlay schedule. (MPSC Order U-21337) |
| 2001 | Overlay approval | U-12880 | MPSC approved all-services distributed overlay introducing 679 NPA for 313/734. Implementation deferred due to conservation measures. (MPSC Order U-12880) |
| 2022-2023 | Implementation petition | U-21337 | NANPA filed petition November 16, 2022. MPSC approved overlay implementation May 18, 2023 with 19-month schedule. Public hearing held March 9, 2023 at Wayne County Community College. (MPSC Case U-21337) |
| 2023 | Implementation schedule | PL-618 | NANPA published planning letter setting milestones: network preparation October 7, 2024; permissive 10-digit dialing April 7, 2025; mandatory October 7, 2025; earliest 679 CO activation November 7, 2025. (NANPA PL-618) |
County Coverage
Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 313).
| County | Population | Share |
|---|---|---|
| Wayne, MI | 1,049,260 | 97.1% |
| Macomb, MI | 31,383 | 2.9% |
Area Code 313 Family Tree
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All Descendants
Area code 313 was originally assigned in 01-Jan-1947 to serve MI. Over the years, it has generated 7 descendant area codes through a combination of geographic splits and overlays as demand for telephone numbers grew.
Call Context
This area code serves a major metropolitan region with high population density in MI. The primary city is Detroit.
Nearby Area Codes
Area codes geographically closest to 313.
Other Area Codes in Michigan
Area codes that also serve Michigan, linked for easy comparison.