East River, tidal strait, 16 mi (26 km) long and 600–4,000 ft (183–1,219 m) wide, connecting Upper New York Bay and Long Island Sound, New York City, and separating the boroughs of Manhattan and the Bronx from Brooklyn and Queens. The East River is linked with the Hudson River at the northern end of Manhattan island by the Harlem River. Roosevelt (formerly Welfare), Wards, Randalls, Rikers, North Brother, and South Brother islands, all located in the East River, have city institutions, parks, and recreation areas. Roosevelt Island was developed as a residential area in the early 1970s. Hell Gate, at the junction of the Harlem and East rivers, was named for its treacherous currents and rocky reefs (now removed). Eight bridges, including the historic Brooklyn Bridge, span the river; subway, railroad, and vehicular tunnels pass beneath it.