Massachusetts and may be used for further expansion of the Blue Line. Erie Railroad (Rochester Division) In June 1907, the Erie Railroad changed from steam to electric operation on its Rochester Division. A single phase AC system was used operating at . The electrified section was between Rochester, NY to Mount Morris, NY, a distance of . The system lasted in operation until 1934. New York, New Haven and Hartford Railroad The New York, New Haven and Hartford Railroad completed electrification in 1907 of its New Haven–New York City mainline and was one of the pioneers of heavy electric railway use in the United States. The New Haven chose the system, later used by the PRR, in addition to working with Westinghouse to develop AC/DC electric motors (locomotives) to run on both AC overhead lines and DC third rail. The main line, now Metro-North Railroad's New Haven Line, was converted to in 1985. Pennsylvania Railroad The Pennsylvania Railroad carried out many electrification projects. West Jersey and Seashore Railroad The PRR, owner of West Jersey & Seashore Railroad (WJ&S), electrified with from Camden, New Jersey to Atlantic City, via Newfield, and to Millville. A third-rail system was used for most of the line except overhead trolley wire was installed between Mickle Street in Camden and Gloucester City as well as a segment between Newfield and Millville. The Camden-Gloucester City portion was installed due to a decision to use the old Camden Seventh Street line as part of the route. Numerous grade crossings on both this segment and in Gloucester City precluded the use of third rail due to public safety considerations. The Millville branch, however, was equipped with overhead wire as a "method of comparing the durability of trolley wire versus third rail under high-speed open-country operating conditions." The WJ&S ordered 62 coaches and six combination baggage mail units split between Jackson and Sharp Company, and J. G. Brill and Company at Philadelphia, which had 46 cars from the order. Brill sublet work on 22 coaches to its Wason subsidiary in Springfield, Massachusetts. The electrification was opened in 1906 with cars that resembled wooden interurbans of other electric traction properties. The same year the 1906 Atlantic City train wreck occurred, in which a three-car train of the new equipment derailed and fell into a waterway; 53 people died. Other cars were built in 1909 bringing the fleet total to 80 MP1