Perth Amboy is a city in northeastern Middlesex County, in the U.S. state of New Jersey, within the New York metropolitan area. As of the 2020 United States census, the city's population was 55,436, its highest decennial count ever and an increase of 4,622 from the 50,814 recorded at the 2010 census, which in turn had reflected an increase of 3,511 from the 47,303 counted at the 2000 census. Perth Amboy has a Hispanic majority population.