Perth Amboy is a city in Middlesex County, New Jersey. Perth Amboy is part of the New York metropolitan area. As of the 2020 U.S. census, the city's population was 55,436. Perth Amboy has a Hispanic majority population. In the 2010 census, the Hispanic population made up 78.1% of the population, the second-highest in the state, behind Union City at 84.7%. Perth Amboy is known as the "City by the Bay", referring to its location adjoining Raritan Bay.