Early in the 20th century, the Pennsy tried electric power for its trains. Its first effort was in the New York terminal area, where tunnels and a city law restricting the burning of coal precluded steam locomotives. In 1910, the railroad began operating a direct current (DC) 650-volt system whose third-rail powered Pennsy locomotives (and LIRR passenger cars) used to enter Penn Station in New York City via the Hudson River tunnels.
