The connection to the Port Authority Bus Terminal opened in 1950, and a platform on a lower level operated intermittently between 1952 and 1981.

There was originally a lower level with one track and one side platform that served southbound trains from the Queens Boulevard Line.

The station is compliant with the Americans with Disabilities Act of 1990, but the passageway to the Times Square–42nd Street complex is not accessible.

[5] As early as March 1918, soon after the Brooklyn–Manhattan Transit Corporation (BMT)'s Broadway Line opened to Times Square–42nd Street, plans were being considered for an extension of that line beyond the stubs at 57th Street–Seventh Avenue to the Upper West Side and Washington Heights via Central Park West (Eighth Avenue).

[7][8] Mayor John Hylan instead wanted to build an independent subway system, operated by the city.

The New York City Board of Transportation (NYCBOT) gave preliminary approval to several lines in Manhattan, including one on Eighth Avenue, on December 9, 1924.

Neighboring buildings, such as the Times Square Hotel and the Franklin Savings Bank at 42nd Street, had to be underpinned because the station extended all the way to the property line on either side.

[19] The line's opening was expected to spur development around the intersection of 42nd Street and Eighth Avenue.

[25] The IND's lower level was built together with the upper-level platforms but existed as an unfinished shell.

[28][29][30] By the 1970s, city officials planned to raise funds for a renovation of the Times Square station complex, using sales-tax revenue from materials used in the construction of the New York Marriott Marquis hotel.

[34] On August 1, 1988, the passageway between the IND Eighth Avenue Line station and the IRT/BMT complex was finally placed within fare control.

[37] As part of the redevelopment, in 1988, the state and NYCTA announced that they would spend $125 million on renovating the Times Square subway complex.

[36] The project was canceled in August 1992 after Prudential Insurance and Park Tower Realty was given permission to postpone the construction of these buildings.

[41] In the late 2000s, the MTA began construction on an extension of the IRT Flushing Line to 34th Street, which would require demolishing the IND Eighth Avenue lower level platform.

Formerly, it also had a lower level with a single side platform, which could be served by southbound trains from the IND Queens Boulevard Line.

[14] Both island platforms were originally 600 feet (180 m) long,[50] although the station served 660-foot-long (200 m), 11-car trains on the E route from 1953[52] to 1958.

[50] At 41st Street, the station crosses over the IRT Flushing Line tunnels; this overpass required 217,000 pounds (98,000 kg) of steel.

The lower level featured two high-speed escalators to the mezzanine, and three staircases to the southbound island platform.

[50] Reportedly, this would have allowed E trains to load and unload passengers without having to wait for one of the two upper level tracks to clear.

[57] The New York Herald Tribune wrote in 1928: "The construction is such as will enable the engineers to extend the Queensboro subway under and beyond Eighth Avenue in the direction of the 42nd Street ferry if desired".

[61]: 7, 18 The Port Authority and Times Square stations contain several artworks commissioned as part of the MTA Arts & Design program.

In 1991, Norman B. Colp created The Commuter's Lament or A Close Shave, a series of signs attached to the roof of the 41st Street passageway between Seventh and Eighth Avenues, inspired by classic Burma-Shave ads.

[65] The 42nd Street–Port Authority Bus Terminal station contains the mosaic artwork Losing My Marbles, which was created by Lisa Dinhofer and installed in 2003.