Construction and opening

Planning for a subway line in New York City dates to 1864.^[5]: 21 However, development of what would become the city's first subway line did not start until 1894, when the New York State Legislature authorized the Rapid Transit Act.^{[5]: 139–140} The subway plans were drawn up by a team of engineers led by William Barclay Parsons, chief engineer of the Rapid Transit Commission. 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.^[6]: 3 A plan was formally adopted in 1897, and legal challenges were resolved near the end of 1899.^[5]: 148 The Rapid Transit Construction Company, organized by John B. McDonald and funded by August Belmont Jr., signed the initial Contract 1 with the Rapid Transit Commission in February 1900,^[7] in which it would construct the subway and maintain a 50-year operating lease from the opening of the line.^[5]: 165 In 1901, the firm of Heins & LaFarge was hired to design the underground stations.^[6]: 4 Belmont incorporated the Interborough Rapid Transit Company (IRT) in April 1902 to operate the subway.^[5]: 182

The IRT's East Side Branch now the Lenox Avenue Line was largely constructed as part of Section 8, built by Farrell & Hopper. The company began building the section from 110th Street to 135th Street on August 30, 1900, and the section from 103rd Street to 110th Street and Lenox Avenue on October 2, 1900.^{[7][8]: 252} The excavation was relatively easy because the subway was under one side of Lenox Avenue and, as such, there were no street railway tracks to work around.^{[8]: 252–253} At Lenox Avenue and 110th Street, a 6.5-foot (200 cm) diameter circular brick sewer, draining 124 acres (50 ha) of the west side of Manhattan, was intersected by the subway. A new sewer of equal diameter, but to a depth sufficient to pass beneath the subway was constructed on either side of the subway structure. Where the sewer passed beneath the subway, the brick sewer was replaced by three 42-inch (110 cm) diameter cast iron pipes.^[8]: 240

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.^[9]: 7 North of the junction, the line would have continued to the 33-track Lenox Yard; this segment was part of Section 9A.^{[4]: 9–10} McMullan & McBean began work on Section 9A on September 10, 1901.^{[10][11]: 253} The 142nd Street Junction was built under soft soil due to its proximity to the shoreline of the Harlem River. As such, the contractors could not build a flying junction; instead, the tracks from the yard were to cross over the revenue-service tracks at a level junction. There originally would not have been any stations between the junction and the yard, but a station at 145th Street was added to the plan in 1903.^[4]: 10

A map of the Lenox Avenue Line from 1906

The line opened south of 145th Street just after midnight on November 23, 1904, as part of the IRT's original system. It was known as the East Side Subway or East Side Branch at the time, as it was the spur of the main line to the east side.^[12] The first train ran from the line onto the IRT White Plains Road Line (known as the West Farms Branch or the West Farms Extension) just after midnight on July 10, 1905.^[13] Soon after the line opened, it was speculated that it would bring prosperity to Harlem.^[14] The line ran across the path of the Harlem Creek, a creek that had once been located above ground but had been buried by the first decade of the 20th century.^[15] The creek's presence caused flooding in the line's early years, especially around 116th Street.^[16] In April 1907, IRT officials decided to create a concrete drain beneath the Lenox Avenue Line tunnel, during which time trains in both directions ran on the southbound track during late nights.^[17] In Fiscal Year 1910, the bottom of the tunnel at the south end of the 116th Street station was rebuilt to prevent leaking.^[18]

Later history

The line has always carried trains of two service patterns. Initially, the station was served by both local and express trains. Local trains operated only to 145th Street, while express trains ran to either 145th Street or West Farms (180th Street).^[19] Express trains to 145th Street were eliminated in 1906.^[20] To address overcrowding, in 1909, the New York Public Service Commission proposed lengthening platforms at stations along the original IRT subway.^[21]: 168 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. It was anticipated that these improvements would increase capacity by 25 percent.^[22]: 15 On January 23, 1911, ten-car express trains began running on the East Side Line.^{[21]: 168 [23]}

In 1918, the Broadway–Seventh Avenue Line opened south of Times Square–42nd Street, thereby dividing the original line into an H-shaped system.^[24] The city government took over the IRT's operations on June 12, 1940.^[25][26] The IRT routes were given numbered designations with the introduction of "R-type" rolling stock;^[27] 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.^[28] Prior to February 6, 1959, 3 trains switched to the local on the IRT Broadway–Seventh Avenue Line north of 96th Street. Afterwards, all trains running from the Lenox Avenue Line ran express.^[29][30][31] The Harlem–148th Street station was opened on May 13, 1968, on land that had been part of the Lenox Yard; the station was originally called Lenox Terminal–148th Street.^[32]

Starting on March 2, 1998, the tunnel was reconstructed along with the cracked invert (tunnel floor). This was done to correct a major water problem that had existed for many years due to the continued 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.^[33][34] The project cost $82 million and was finished on October 12, 1998.^[33][35] During the reconstruction, many 2 trains were rerouted via the IRT Lexington Avenue Line, while the 3 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, the 116th Street station was closed, and supplemental shuttle bus service connecting to other lines in the area were provided for much of this time.^[36][37]

From 1995 until 2008, the line's two northernmost stations, Harlem–148th Street and 145th Street, were served by shuttle buses during the late-night hours. Full-time service was restored on July 27, 2008.^[38]

On March 27, 2020, a northbound 2 train caught fire while approaching Central Park North–110th Street, the southernmost station on the line. The fire killed the train's motorman and injured 16. Subway service on the Lenox Avenue Line resumed on March 30, bypassing the Central Park North station until it reopened on April 6.^[39][40]