Hamilton, township, Mercer County, western New Jersey, between Crosswick and Assunpink creeks, near Trenton. It is a residential community with varied manufacturing. Communities within the township include Hamilton Square, Yardville, Mercerville, and White Horse. A community college and an automobile racetrack are here. The former New Jersey State Fair Grounds, also in Hamilton, is the location of a sculpture park. Population 82,801 (1980); 86,553 (1990).