Staten Island /ˌstætən ˈaɪlənd/ is one of the five boroughs of New York City, in the U.S. state of New York. In the southwest of the city, Staten Island is the southernmost part of both the city and state of New York, with Conference House Park at the southern tip of the island and the state. The borough is separated from New Jersey by the Arthur Kill and the Kill Van Kull, and from the rest of New York by New York Bay. With a 2014 Census-estimated population of 473,279, Staten Island is the least populated of the boroughs but is the third-largest in area at 58 sq mi (150 km²). The borough is coextensive with Richmond County, and until 1975 was officially the Borough of Richmond. Its flag was later changed to reflect this, though the official seal remains unchanged.