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, under which it would construct the subway and maintain a 50-year operating lease from the opening of the line. Belmont incorporated the
Interborough Rapid Transit Company (IRT) in April 1902 to operate the subway. At the time, the section of 125th Street in West Harlem was known as Manhattan Street; although engineers found that it was technically feasible to dig a tunnel under Manhattan Street, they concluded that such a tunnel would have required a steep grade. The IRT's engineers originally planned to build a standard elevated structure, similar to those built in other parts of the rapid transit system, with steel columns that supported
plate girder spans. However, this plan would have required rerouting the
Third Avenue/125th Street streetcar line, which ran along Manhattan Street. As such, prior to the start of construction, the plans were changed to a steel viaduct with a double-hinged arch. The elevated rail section runs from 122nd to 135th Street and was originally called the Manhattan Valley Viaduct. According to
Tramway and Railway World magazine, the viaduct was built within two weeks. A third track was added directly north of
96th Street, immediately east of the originally planned two tracks. By late 1903, the subway was nearly complete, but the
IRT Powerhouse and the system's
electrical substations were still under construction, delaying the system's opening. The escalators had not been installed by the time the station was scheduled to open, forcing passengers to use temporary stairways. The 125th Street station opened on October 27, 1904, as the Manhattan Street station, one of the original 28 stations of the New York City Subway from
City Hall to
145th Street on the West Side Branch. the station was served by West Side local and express trains. Express trains began at
South Ferry in Manhattan or
Atlantic Avenue in Brooklyn, and ended at
242nd Street in the Bronx. Local trains ran from City Hall to 242nd Street during rush hours, continuing south from City Hall to South Ferry at other times. 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. The original subway north of Times Square thus became part of the Broadway–Seventh Avenue Line. Local trains were sent to
South Ferry, while express trains used the new
Clark Street Tunnel to Brooklyn. 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 northbound platform at the Manhattan Street station was extended about to the south, Subsequently, the station could accommodate six-car local trains, but ten-car trains could not open some of their doors. Manhattan Street was renamed 125th Street on April 24, 1921; the original alignment of 125th Street became known as LaSalle Street. A mezzanine below the tracks opened at the station on September 26, 1931, with three new escalators and a new staircase to and from the street. The span of escalator service was extended from 1 a.m. to 2 a.m. on November 2, 1931. The city government took over the IRT's operations on June 12, 1940. Platforms at IRT Broadway–Seventh Avenue Line stations between and , including those at 125th Street, were lengthened to in 1948, allowing full ten-car express trains to stop at these stations. The platform extensions at these stations were opened in stages. The platform extensions at 125th Street opened on June 11, 1948. Simultaneously, the IRT routes were given numbered designations with the introduction of
"R-type" rolling stock, which contained
rollsigns with numbered designations for each service. The route to 242nd Street became known as the
1. In 1959, all 1 trains became local. On November 24, 1981, the
New York City Landmarks Preservation Commission (LPC) designated the Manhattan Valley Viaduct, including the 125th Street station, as a city landmark. The designation was contentious; the Jewish Theological Seminary argued against the designation because it would prevent the museum from erecting a new structure on or near the site. The
New York City Board of Estimate, which had to ratify the landmark status, upheld the designation in April 1982. The viaduct and station were added to the
National Register of Historic Places in 1983. In April 1988, the
New York City Transit Authority (NYCTA) unveiled plans to speed up service on the Broadway–Seventh Avenue Line through the implementation of a
skip-stop service: the
9 train. As soon as the plan was announced, some local officials were opposed to the change. Initially, skip-stop service would have been operated north of
116th Street, with 1 trains skipping 125th Street,
157th Street,
207th Street, and
225th Street, and 9 trains skipping
145th Street,
181st Street,
Dyckman Street,
215th Street and
238th Street. However, the plan was changed because riders did not want 125th Street to be a skip-stop station.
21st century In June 2002, the
Metropolitan Transportation Authority (MTA) announced that ten subway stations citywide, including
103rd Street,
110th Street,
116th Street, 125th Street, and
231st Street on the IRT Broadway–Seventh Avenue Line, would receive renovations. As part of the project, fare control areas would be redesigned, flooring, and electrical and communication systems would be upgraded, and new lighting, public address systems and stairways would be installed. In addition, since 110th Street, 116th Street, and 125th Street had landmark status, historical elements would be replaced or restored, including wall tiles. Work on the ten citywide renovation projects was estimated to cost almost $146 million, and was scheduled to start later that year, and be completed in April 2004, in time for the 100th anniversary of the station's opening, and the 250th anniversary of Columbia University.
Manhattan Community Board 9 was concerned about preserving the historic nature of the station during its renovation.
Manhattan Community Board 7 got the MTA to agree to maintain the existing design of the wood paneling and windows in the station. The MTA was expected to decide whether preservation or speed would be prioritized in the station renovation projects by the end of the year. Columbia University provided funding to cover a portion of the cost of renovating the 125th Street station, as it did for the station renovations at 103rd Street, 110th Street, and 116th Street, and funded the substitution of the station's aluminum vents with glass windows to reflect the station's original design. Between October 5 and November 17, 2003, the downtown platforms at 110th Street and 125th Street were closed to expedite work on their renovations. Skip-stop service ended on May 27, 2005, as a result of a decrease in the number of riders who benefited. In February 2022, local officials requested that the MTA consider adding elevators to the 125th Street station, citing the fact that West Harlem was growing rapidly. At the time, there was only one fully accessible subway station on the Broadway–Seventh Avenue Line north of
96th Street; that station was 231st Street, several miles north in
the Bronx. Despite calls from local residents,
Columbia University, which was developing a 34-story building adjoining the station, originally refused to pay for any of the elevators; it instead offered only to fund the cost of escalators. In April 2026, Columbia agreed to pay $33 million for new escalators and a street-to-mezzanine elevator. Under this plan, the MTA would pay for two additional elevators from mezzanine to platform level. 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 ==