The 145th Street station was constructed as part of the IRT's East Side Branch (now the Lenox Avenue Line). The original plan envisioned a station on the Lenox Avenue Line at 141st Street, just south of the 142nd Street Junction, where a spur of the Lenox Avenue Line diverges to the Bronx via the IRT White Plains Road Line. This was ultimately not built, and instead, the 145th Street station became the last stop on the Lenox Avenue Line before it entered the Lenox Yard, a train maintenance yard immediately to the north. McMullan & McBean began work on the section from 135th Street and Lenox Avenue to Gerard Avenue and 149th Street, including the 145th Street spur, on September 10, 1901.