Third rail
As part of the construction of Grand Central Terminal in the early 1900s, all of New York Central's lines that ran into the terminal were electrified. Third rail was installed on the Hudson and Harlem Divisions, while the New Haven Division received overhead wires on the segments that were not shared with the Harlem and Hudson Division. In November 1907, the first electric train operated on the Harlem Division, running between Grand Central Terminal and Wakefield. On October 10, 1909, the New York Central began installing third rail between Mount Vernon and White Plains. On March 14, 1910, electric service was extended to North White Plains. Passengers that used the Upper Harlem Division were attracted to this cleaner, faster service.