Construction and opening Planning for a
subway line in New York City dates to 1864. The subway plans were drawn up by a team of engineers led by
William Barclay Parsons, the Rapid Transit Commission's chief engineer. It called for a subway line from
New York City Hall in
lower Manhattan to the
Upper West Side, where two branches would lead north into
the Bronx. A plan was formally adopted in 1897, and legal challenges were resolved near the end of 1899. in which it would construct the subway and maintain a 50-year operating lease from the opening of the line. The excavation was relatively easy because the subway was under one side of Lenox Avenue and there were no street railway tracks to work around. Initially, the station was served by East Side local and express trains. Local trains ran from
City Hall to
Lenox Avenue (145th Street). Express trains had their southern terminus at
South Ferry or
Atlantic Avenue and had their northern terminus at 145th Street or
West Farms (
180th Street). Express trains to 145th Street were eliminated in 1906, and West Farms express trains operated through to Atlantic Avenue in Brooklyn.
Service changes and station renovations To address overcrowding, in 1909, the
New York Public Service Commission proposed lengthening the platforms at stations along the original IRT subway. As part of a modification to the IRT's construction contracts made on January 18, 1910, the company was to lengthen station platforms to accommodate ten-car express and six-car local trains. In addition to $1.5 million (equivalent to $ million in ) spent on platform lengthening, $500,000 (equivalent to $ million in ) was spent on building additional entrances and exits. It was anticipated that these improvements would increase capacity by 25 percent. The platforms at the 125th Street station were extended to both the north and south. In 1918, the
Broadway–Seventh Avenue Line opened south of
Times Square–42nd Street, and the original line was divided into an H-shaped system. Local trains were sent to
South Ferry, while express trains used the new
Clark Street Tunnel to Brooklyn. The city government took over the IRT's operations on June 12, 1940. The IRT routes were given numbered designations with the introduction of
"R-type" rolling stock. These fleet contained
rollsigns with numbered designations for each service. The first such fleet, the
R12, was put into service in 1948. The route to White Plains Road, formerly the route to West Farms, became known as the
2, while the route to Lenox Avenue–145th Street became the
3. The
New York City Transit Authority (NYCTA) announced plans in 1956 to add
fluorescent lights above the edges of the station's platforms. In 1959, all 2 and 3 trains became express. In November 1959, the Warshaw Construction Company received a contract to remove fifteen entrance/exit kiosks on IRT lines, including four at the 125th Street station. This was part of a citywide initiative to remove the kiosks, which obstructed motorists' views of pedestrians. On May 23, 1968, poet
Henry Dumas was fatally shot by a
New York City Transit Police officer on the station's southbound platform. In 1981, the
Metropolitan Transportation Authority listed the station among the 69 most deteriorated stations in the subway system. Starting on March 2, 1998, the tunnel was reconstructed along with the cracked tunnel floor. This was done to correct a major water problem that had existed for many years due to the presence of the Harlem Creek and other
underground streams, which caused extensive flooding, water damage, and seepage problems that occasionally contributed to severe service disruptions. The project cost $82 million and was finished on October 12, 1998. During the reconstruction, many trains were rerouted via the
IRT Lexington Avenue Line, while the trains were rerouted to the
137th Street–City College station on the
IRT Broadway–Seventh Avenue Line. Each of the two Lenox Avenue Line tracks were alternately taken out of service and supplemental shuttle bus service connecting to other lines in the area were provided for much of this time. The MTA announced in 2024 that it would replace the station's existing
waist-high turnstiles with taller, wide-aisle turnstiles. As part of its 2025–2029 Capital Program, the MTA has proposed making the station wheelchair-accessible in compliance with the
Americans with Disabilities Act of 1990. In January 2026, Governor
Kathy Hochul announced that she would request funding to extend the
Second Avenue Subway along 125th Street. Although
Phase 2 of the line's construction was initially planned to extend only to
125th Street and Lexington Avenue, Hochul's proposal called for additional connections to existing stations at Lenox Avenue,
St. Nicholas Avenue, and
Broadway. ==Station layout==