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.

Navigable tidal strait in the U.S. linking Upper New York Bay with Long Island Sound in New York City. It separates Manhattan and the Bronx from Brooklyn and Queens. About 16 mi (26 km) long and 600–4,000 ft (200–1200 m) wide, it connects with the Hudson River via the Harlem River and Spuyten Duyvil Creek at the northern end of Manhattan Island. Roosevelt (formerly Welfare), Wards, Randalls, and Rikers islands are in the East River, which has numerous port facilities.

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