Croton Aqueduct (krō`tən), 38 mi (61 km) long, SE N.Y., carrying water from the Croton River basin to New York City; built 1837–42. It was one of the earliest modern aqueducts in the United States. Water impounded by New Croton Dam (completed 1905) is channeled S to the Bronx, for most of its length in a covered trench along the surface. Water is carried over the Harlem River into Manhattan by Highbridge, a Roman-type aqueduct bridge. New Croton Aqueduct (built 1885–91), 30.5 mi (49 km) long, supplements the flow of Croton Aqueduct. Deep underground tunnels, including one under the Harlem River, channel water from this aqueduct to New York City.