Somerset County, New Jersey

County seat: Somerville · Population 356,486 (2025) · 302 sq mi

Somerset County is the 13th most populous of New Jersey's 21 counties, with 356,486 people (2025 estimate). Its county seat is Somerville. The map shows its 12 cities and towns and the 5 neighboring counties.

Map of Somerset County, New Jersey with cities, towns and the county boundary
Somerset County, New Jersey with its cities and towns, unincorporated communities (CDPs) and neighboring counties. Boundaries: U.S. Census Bureau, 2025. Free to use with attribution (CC BY 4.0).
Download PDF (Letter) 178 KBPNG image 142 KBNew Jersey county map

Somerset County facts

County seat
Somerville
Population (2025 estimate)
356,486 +3.2% since 2020
Land area
302 sq mi 13th largest of 21
Water area
3 sq mi
Population density
1,181 per sq mi
Established
1688
Same name
One of 4 Somerset Counties in the US
Named after
Somerset ceremonial county of England (use Q21694741 for administrative non-metropolitan county)
Largest city
Franklin 69,105
Median household income
$140,374
Cities and towns
12 plus 38 CDPs
ZIP codes
33
Time zone
Eastern
FIPS code
34035

Cities and towns in Somerset County

Somerset County has 12 incorporated cities, towns and villages. Populations count the people living inside Somerset County; cities that cross a county line also list the other counties.

NameTypePopulation 2025Also in
North PlainfieldBorough22,879
Somerville (county seat)Borough14,665
Bound BrookBorough13,038
ManvilleBorough10,932
RaritanBorough8,516
BernardsvilleBorough7,966
WatchungBorough6,583
South Bound BrookBorough4,926
Peapack and GladstoneBorough2,587
Far HillsBorough974
Rocky HillBorough751
MillstoneBorough456

Unincorporated communities (CDPs)

Census-designated places are communities without their own city government; the county provides their services.

CommunityPopulationAlso in
Somerset22,720
Hillsborough22,585
Bradley Gardens14,165
Franklin Park13,211
Martinsville11,559
East Franklin11,070
The Hills10,785
Blackwells Mills10,301
Basking Ridge7,917
Green Knoll6,789
Franklin Center6,646
Bridgewater Center6,505
Finderne6,489
Belle Mead6,394
Neshanic Station5,438Hunterdon County
Lyons5,187
Six Mile Run2,882
Ten Mile Run2,492
Liberty Corner2,325
Weston2,105
Middlebush2,049
Voorhees2,000
Bedminster1,670
Flagtown930
Griggstown812
East Millstone698
Neshanic626
Harlingen593
Pluckemin489
Pleasant Plains468
Lamington362
Skillman345
East Rocky Hill235
Kingston160Middlesex County
Clyde129
Blawenburg85
Pottersville67Hunterdon County
Zarephath17

ZIP codes in Somerset County

33 ZIP codes reach into Somerset County. ZIP codes ignore county lines, so some also cover a neighboring county.

Population of Somerset County, 2020–2025

Somerset County grew by 11,137 people (+3.2%) between April 2020 and July 2025: 2,736 more births than deaths and a net gain of 8,290 people from migration.

Year (July 1)Population
2020344,516
2021346,069
2022347,621
2023351,042
2024355,122
2025356,486

Neighboring counties

Printable Somerset County map

The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.

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Sources

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