It is the southernmost station on the IRT Jerome Avenue Line. To the south, the line crosses the Harlem River into East Harlem, Manhattan and the three tracks merge into two and merge with the IRT Pelham Line to form the four-track IRT Lexington Avenue Line. To the north, the local tracks split into two. One set of tracks (the inner set) continues along Jerome Avenue, and the other set of tracks (the outer set) descends to a lower level and makes a sharp turn to merge with the IRT White Plains Road Line directly west of 149th Street–Grand Concourse. The 5 train uses these tracks during daytime hours.