Somerset County is a county located in the U.S. state of New Jersey.

Somerset County is one of America's oldest counties, and is named after the English county of Somerset. The area was first settled in 1681.

Most of the early residents were Dutch. General George Washington and his troops marched through the county on several occasions and slept in many of the homes located throughout the area. Somerset County also played an important part during both World War I and World War II with weapons depots and the manufacturing of the army's woolen blankets.

Somerset County was primarily an agricultural county. In the late 19th century, the county saw many wealthy people come to live. The area is still the home of several wealthy people who were in the pharmaceutical industry.^[1]

In the 1960s, townships that were once exclusively agricultural were quickly transformed into suburban communities. Examples include Bridgewater Township^[2] and the Watchung Hills communities of Watchung, Green Brook and Warren Township.^[3][4][5]

At the 2020 United States Census, there were 345,361 people, 125,598 households, and 90,945 families living in the county. The population density was 1,144.1 per square mile (441.7/km²).^[6][7]

At the 2010 United States Census, there were 323,444 people, 117,759 households, and 84,669 families living in the county. The population density was 1,071.7 per square mile (413.8/km²).

At the 2000 United States Census,^[8] there were 297,490 people, 108,984 households and 78,359 families living in the county. The population density was 976 per square mile (377/km²).^{[9][10][10][11]}

Municipalities in Somerset County are below.^[12] A CDP is a Census-designated place, as described by the Census Bureau.

Somerset County has numerous roads. As of May 2010^[update], the county had a total of 1,714.99 miles (2,760.01 km) of roadways. 1,370.80 miles (2,206.09 km) were maintained by the towns. 234.23 miles (376.96 km) were maintained by Somerset County and 109.96 miles (176.96 km) were by the New Jersey Department of Transportation.^[14]

The only two state routes that traverse through are Route 27 (only in Franklin) and Route 28.

U.S. Routes include U.S. Route 22, U.S. Route 202 and U.S. Route 206. The two interstates that pass through are Interstate 78 and Interstate 287.

Route 18 runs at the New Brunswick border of Somerset.

New_Jersey_Transit provides train service. It operates Raritan_Valley_Line.^[15][16]It can go to New York City. PPublic bus transportation is provided by several transit agencies.^[17]

NJ Transit provides bus service Midtown Manhattan, as well as service to major cities in New Jersey and within Somerset County.^{[18] [19]}