The Brooklyn–Battery Tunnel, officially known as the Hugh L. Carey Tunnel, is a toll road in New York City which crosses under the East River at its mouth, connecting the Borough of Brooklyn on Long Island with the Borough of Manhattan. The tunnel nearly passes underneath Governors Island, but does not provide vehicular access to the island. It consists of twin tubes, carrying four traffic lanes, and at 9,117 feet (2,779 m) is the longest continuous underwater vehicular tunnel in North America. It was opened to traffic in 1950. It currently carries the unsigned Interstate 478 (I-478) designation, and formerly carried New York State Route 27A (NY 27A).