Somerset County is a county located in the U.S. state of New Jersey. As of the 2010 United States Census, the county's population was 323,444, increasing by 25,954 (+8.7%) from the 297,490 counted in the 2000 Census, retaining its position as the state's 13th-most populous county. It is part of the New York Metropolitan Area. Its county seat is Somerville.
Somerset County is the ninth-wealthiest county in the United States by per capita income and the highest in New Jersey. The Bureau of Economic Analysis ranked the county as having the 11th-highest per capita income of all 3,113 counties in the United States (and the highest in New Jersey) as of 2009. The county also ranks eighth in the United States in terms of median income.
Somerset County was created on May 14, 1688, from portions of Middlesex County.