electric service on its Harlem River Branch: a suburban branch that would become a main line with the completion of the New York Connecting Railroad and its Hell Gate Bridge. The bridge opened on March 9, 1917, but was operated by steam with an engine change at Sunnyside Yard east of Penn Station until 1918. Electrification north of New Haven to Providence and Boston had been planned by the NH, and authorized by the company's board of directors shortly before the United States entered World War I. This plan was not carried out because of the war and the company's financial problems. Electrification north of New Haven did not occur until the 1990s, by AMTRAK, using a 60 Hz system. New York to Washington electrification In 1905, the PRR began to electrify its suburban lines at Philadelphia: an effort that eventually led to 11 kV, 25 Hz AC catenary from New York and Washington. Electric service began in September 1915, with multiple unit trains west to Paoli on the PRR Main Line (now the Keystone Corridor). Electric service to Chestnut Hill (now the Chestnut Hill West Line), including a stretch of the NEC, began on March 30, 1918. Local electric service to Wilmington, Delaware, on the NEC began on September 30, 1928, and to Trenton, New Jersey, on June 29, 1930. Electrified service between Exchange Place, the Jersey City terminal, and New Brunswick, New Jersey, began on December 8, 1932, including the extension of Penn Station electric service from Manhattan Transfer. On January 16, 1933, the rest of the electrification between New Brunswick and Trenton opened, giving a fully-electrified line between New York and Wilmington. Trains to Washington began running under electricity to Wilmington on February 12, 1933, with the engine-change moved from Manhattan Transfer to Wilmington. The same was done on April 9, 1933, for trains running west from Philadelphia, with the change point moved to Paoli. In 1933, the electrification south of Wilmington was stalled by the Great Depression, but the PRR got a loan from the Public Works Administration to resume work. The tunnels at Baltimore were rebuilt as part of the project. Electric service between New York and Washington began on February 10, 1935. On April 7, the electrification of passenger trains was complete, with 639 daily trains: 191 hauled by locomotives and the other 448 under multiple-unit power. New York–Washington electric freight service began on