were introduced into regular passenger service on November 27, 1910 to operate in the North River Tunnels under the Hudson River. As steam locomotives were prohibited from entering the tunnels, the electric DD1 shuttled passengers from the Pennsylvania Railroad's Manhattan Transfer station in New Jersey and Pennsylvania Station in New York City. A total of 66 locomotives were constructed by the Pennsylvania Railroad's Juniata Shops in Altoona starting in 1909; 3936 and 3937 were put into service in 1911. As the new L5s were being introduced in 1924, most DD1s were transferred to the Long Island Rail Road. Both 3936 and 3937 were shifted from mainline passenger duty, and hauled the empty passenger trains from Pennsylvania Station to Sunnyside Yard. The Long Island Rail Road scrapped most of its DD1s from 1949 to 1951, and only two pairs remained in 1962. By 1978, Nos. 3936 and 3937 comprised the last existing DD1 and were donated to the Railroad Museum of Pennsylvania in Strasburg, Pennsylvania by the Pennsylvania's successor Penn Central, as part of a collection with twelve other historically-significant locomotives. Both locomotives were jointly listed on the National Register of Historic Places on December 17, 1979. Gallery See also PRR locomotive classification Footnotes References Further reading External links LIRR Early Electric Engines (TrainsAreFun.com) Long Island Rail Road DD1-344 and 348 at Morris Park Shops (New Dave's Rail Pix) 2-Bo-Bo-2 locomotives DD1 600 V DC locomotives Electric locomotives of the United States Standard gauge locomotives of the United States Railway locomotives introduced in 1911 Passenger locomotives