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). The tunnel was officially named after former New York Governor Hugh Carey in December 2010.
Construction began on October 28, 1940 by the New York City Tunnel Authority, with a groundbreaking ceremony attended by President Franklin D. Roosevelt. A large part of Little Syria, a mostly Christian Syrian/Lebanese neighborhood centered around Washington Street, was razed to create the entrance ramps for the tunnel. The shops and residents of Little Syria later moved to Atlantic Avenue in Brooklyn.The tunnel was designed by Ole Singstad and partially completed when World War II brought a halt to construction. After the War, the Triborough Bridge Authority was merged with the Tunnel Authority, allowing the new Triborough Bridge and Tunnel Authority (TBTA) to take over the project. TBTA Chairman Robert Moses directed the tunnel be finished with a different method for finishing the tunnel walls. This resulted in leaking and, according to Robert Caro, the TBTA fixed the leaks by using a design almost identical to Singstad's original.The tunnel opened to traffic on May 25, 1950.