Somerset County, New Jersey

Somerset County is a county in New Jersey, United States, about 35 miles west of New York City. It had a population of 345,361 at the 2020 census, an estimated 356,486 by 2025, and covers 301.87 square miles (781.8 km2) of land centred near 40°34′N 74°37′W.

Somerville is the county seat; its postal code is 08876. The county is divided into 9 townships and 12 boroughs — 21 municipalities in all, and no unincorporated territory, since New Jersey’s home-rule system places every acre inside one municipal government or another. It runs on Eastern time. Its FIPS code is 34035.

Towns & Villages in Somerset County

Somerset County has 21 municipalities: 9 townships and 12 boroughs. New Jersey townships and boroughs are both full municipal governments, not subdivisions of a larger town, so every place below is its own incorporated jurisdiction.

Franklin Township, the county’s largest municipality by population, contains an unincorporated community called Somerset — a Census-designated place of about 23,000 people that shares its ZIP code (08873) with the wider Franklin Township area. Somerset the place and Somerset the county are two different things: the CDP sits entirely inside Franklin Township and has no government of its own, while the county spans all 21 municipalities listed above. Mail addressed to “Somerset, NJ” and mail addressed to a Somerset County town elsewhere in the county are not interchangeable.

ZIP Codes

• 07921 — Bedminster
• 07920 — Basking Ridge (serves Bernards Township)
• 07924 — Bernardsville
• 08805 — Bound Brook
• 08807 — Bridgewater
• 07931 — Far Hills
• 08873 — Somerset (serves most of Franklin Township)
• 08823 — Franklin Park (serves part of Franklin Township)
• 08812 — Green Brook
• 08844 — Hillsborough (also serves Millstone borough)
• 08835 — Manville
• 08502 — Belle Mead (serves part of Montgomery Township)
• 08558 — Skillman (serves part of Montgomery Township)
• 07060 — North Plainfield
• 07977 — Peapack (serves part of Peapack-Gladstone)
• 07934 — Gladstone (serves part of Peapack-Gladstone)
• 08869 — Raritan
• 08553 — Rocky Hill
• 08876 — Somerville (also serves Branchburg)
• 08880 — South Bound Brook
• 07059 — Warren
• 07069 — Watchung

Branchburg and Millstone have no ZIP code of their own: Branchburg addresses are filed under Somerville’s 08876, and tiny Millstone borough (448 people) under Hillsborough’s 08844.

Geography

Somerset County sits in north-central New Jersey, split between the Piedmont lowlands and the Watchung Mountains along its eastern edge. Mine Mountain, near Bernardsville, is the county’s highest point at roughly 860 feet; the lowest ground is near sea level along the Raritan River where it crosses into Middlesex County. The North Branch and South Branch of the Raritan River join near Raritan borough and Bridgewater to form the main Raritan River, which then runs east through Bound Brook and South Bound Brook. The Millstone River drains the county’s southern townships, including Montgomery and Franklin, before joining the Raritan in Middlesex County. The Sourland Mountain ridge crosses the southern part of the county around Hillsborough and Montgomery.

Somerset County borders Hunterdon County to the west, Morris County to the north, Union County to the east, Middlesex County to the southeast, and Mercer County to the south.

Demographics

Somerset County had 345,361 residents at the 2020 census, up 6.8% from 2010, with an estimated 356,486 people by 2025. Franklin Township is the most populous municipality at 68,364, followed by Bridgewater Township at 45,977; together they hold about a third of the county’s population. Population density works out to roughly 1,144 people per square mile of land. Median household income was $111,587 (2019 American Community Survey), among the highest of New Jersey’s 21 counties, and 2015 per-capita income of $86,468 ranked second-highest in the state. As of the 2012 estimate, 49.8% of county residents held a bachelor’s degree or higher, the highest share of any New Jersey county.

Economy & Local Life

Somerset County anchors a stretch of the Interstate 78/287 corridor known for corporate headquarters and pharmaceutical research. Verizon’s corporate headquarters sits in Basking Ridge (Bernards Township); AT&T runs a major campus in Bedminster; and Sanofi’s US headquarters is in Bridgewater. The county’s economy shifted from farmland to office parks and pharmaceutical labs through the 1960s-90s, and county GDP reached $39.8 billion in 2021, sixth highest among New Jersey’s counties. Duke Farms, the former Doris Duke estate in Hillsborough, is now a 2,700-acre public nature preserve and one of the county’s largest visitor draws. The Somerset County 4-H Fair, held every August at North Branch Park in Bridgewater, is the county’s largest annual community event.

History

Somerset County was created on May 14, 1688, from part of Middlesex County, and takes its name from the English county of Somerset. Dutch farmers settled the Raritan Valley around Bound Brook from the 1680s onward. During the Revolutionary War, General George Washington’s Continental Army wintered twice in the county at the Middlebrook encampments (1777 and 1778-79); the Wallace House in Somerville served as his headquarters during the second encampment, and it still stands as a state historic site. In the early 20th century, Manville grew up around a Johns-Manville asbestos-products plant that became the borough’s main employer for decades; the site’s asbestos contamination later made it an EPA Superfund cleanup, a legacy still managed today. The county shifted from an agricultural economy to a suburban and corporate one after World War II, driven by the growth of the pharmaceutical and technology sectors along the new interstate highways.

Getting There

Interstate 78 crosses the county’s north, Interstate 287 runs north-south through its center, and Routes 202 and 206 provide the older north-south links. NJ Transit’s Raritan Valley Line stops at Raritan, Somerville, Bridgewater and North Branch, and its Gladstone Branch serves Basking Ridge, Bernardsville, Far Hills and Peapack-Gladstone, both running toward Newark and New York Penn Station.

• New York City — 35 miles northeast
• Newark — 25 miles northeast
• Trenton — 25 miles south
• Princeton — 15 miles south

The nearest major commercial airport is Newark Liberty International, about 30 miles northeast. The nearest Amtrak station is Newark Penn Station, reachable by NJ Transit from Somerville or Raritan.

Frequently Asked Questions

Where is Somerset County, New Jersey?
It sits in north-central New Jersey, about 35 miles west of New York City, bordered by Hunterdon, Morris, Union, Middlesex and Mercer counties.

What is the population of Somerset County?
345,361 at the 2020 census, with an estimated 356,486 residents by 2025.

How big is Somerset County?
301.87 square miles (781.8 km2) of land.

What is the county seat of Somerset County?
Somerville, a borough of 12,346 people, postal code 08876.

How many municipalities are in Somerset County?
21 — 9 townships and 12 boroughs, with no unincorporated territory outside them.

What ZIP codes are in Somerset County?
21 primary ZIP codes, from 07059 (Warren) to 08880 (South Bound Brook); Branchburg and Millstone share their neighbors’ codes rather than having their own.

Is the place called “Somerset” the same as Somerset County?
No. Somerset is an unincorporated community inside Franklin Township, not a separate municipality, though it shares the county’s name and part of its ZIP code (08873).

More counties in this state: Towns and villages in New Jersey.