The Long Island Rail Road's electrification was initiated in the first decade of the 20th century while it was owned by the Pennsylvania Railroad, which was building tunnels under the Hudson River and East River to gain access to Manhattan. The first segment of the LIRR to be electrified was the trackage between the Atlantic Avenue terminal in Brooklyn and Jamaica station. Electrification extended east of Jamaica to the Belmont Park station in 1905. In 1910, the opening of Pennsylvania Station (New York City) ushered in electric service between that station and Jamaica. The LIRR's Port Washington Branch was rebuilt and electrified by 1918. By 1934, LIRR branches to Mineola, Hempstead, West Hempstead, Far Rockaway, Long Beach, and Babylon were electrified. In 1970, electrification was extended to Hicksville, and to Huntington on the Port Jefferson Branch. In 1987, electrification of the Main Line between Hicksville and Ronkonkoma was completed, resulting in greatly increased service.