The construction of the Howard Street tunnel through Baltimore in order to make a rail connection to New York City brought about the world's first mainline electrification. Operation began in 1895 with three General Electric locomotives. These locomotives only worked pulling northbound trains; southbound traffic simply coasted through this section, which was all downhill. Initially the system used a unique overhead track in which the current shoe rode, but shortly after it was converted to a conventional third rail system. The electrification was discontinued in 1952 when dieselization made it unnecessary.