Area Code 631

New York

Area code 631 serves New York, primarily West Babylon, in the Eastern Time (ET) time zone. It has served the region since 01-Nov-1999.

Published: February 17, 2026Verified against NANPA and FCC records

Overlay Area Code

This area code shares its geographic footprint with an overlay code, so the same cities are served by two area codes. Because overlays leave existing numbers untouched, this region's relief planning favors adding codes over redrawing boundaries.

The codes serving this same region: area code 934 (West Babylon).

With prefix utilization already at 97.8%, numbering resources here are under sustained pressure — context that explains why overlays were introduced.

In service since: 01-Nov-1999

Learn more about overlay and split area codes →

Demographics & Economics

Total Population: 1,465,782
Population Density: 1,705 people/sq mi
above U.S. average (U.S.: 95 people/sq mi)
Median Household Income: $130,686
above U.S. median (U.S.: $80,734)
Poverty Rate: 6.4%
below U.S. average (U.S.: 12.5%)
Unemployment Rate: 4.7%
near U.S. average (U.S.: 5.2%)
Education Attainment: Bachelor's Degree+
40.4%
above U.S. average (U.S.: 35.7%)
High School or Lower
30.1%

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

Eastern Time (ET)

Prefix Utilization

Geographic Coverage

State

Major Cities

West Babylon
Coram
Central Islip
Commack
Huntington Station
Centereach
Bay Shore
Shirley
Deer Park
Lindenhurst
West Islip
Holbrook
Medford
Dix Hills
Smithtown
Copiague
Selden
East Patchogue
Hauppauge
North Bay Shore
North Amityville
Huntington
East Northport
Holtsville

and 135 more cities

Area Code 631 geographic coverage map (light mode)

Demographics

The estimated population served by area code 631 is approximately 1,465,782. The population density is 1,705 people per square mile, which is higher than the national average of 95. The median household income is $130,686, which is higher than the national median of $80,734. Approximately 40.4% of adults hold a bachelor's degree or higher, compared to the national rate of 35.7%. This rate is higher than the national average. The poverty rate stands at 6.4%, which is lower than the national rate of 12.5%.

History

Area code 631 was established in 1999 as a geographic area code. It shares its territory with area code area code 934.

County Coverage

Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 631).

County	Population	Share
Suffolk, NY	1,433,004	97.8%
Nassau, NY	32,778	2.2%

Area Code 631 Family Tree

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Total Codes

Splits

Overlays

Max Depth

All Descendants

Code ▲	State	Type	In Service	Parent
934	NY	overlay	16-Jul-2016	631

Area code 631 was originally assigned in 01-Nov-1999 to serve NY. Over the years, it has generated 1 descendant area code through a combination of geographic splits and overlays as demand for telephone numbers grew.