Hamilton Township is a township in Mercer County, New Jersey, United States. The township is within the New York metropolitan area as defined by the United States Census Bureau, but directly borders the Philadelphia metropolitan area and is part of the Federal Communications Commission's Philadelphia Designated Market Area. As of the 2010 United States Census, the township had a total population of 88,464, reflecting an increase of 1,355 (+1.6%) from the 87,109 counted in the 2000 Census, which had in turn increased by 556 (+0.6%) from the 86,553 counted in the 1990 Census. The township was the state's 9th-largest municipality, after having been ranked 10th in 2000. The township is located immediately east of the city of Trenton, the state's capital.