It runs south from Ditmars Boulevard in Astoria to 39th Avenue in Long Island City above 31st Street.

[2][3] It was built as part of the Dual Contracts and jointly operated by the Interborough Rapid Transit Company (IRT) and Brooklyn–Manhattan Transit Corporation (BMT) using IRT-sized cars until 1949, when the platforms were shaved to accept the wider BMT cars and joint service was discontinued.

[2][3][4] The north end of the Astoria Line is a two-track terminal at Ditmars Boulevard, with one island platform.

The whole line north of Queensboro Plaza opened on February 1, 1917 and was used by trains between Grand Central and Astoria.

[7][9] The 60th Street Tunnel opened on August 1, 1920, allowing BMT trains to reach Queensboro Plaza.

However, the stations on the Astoria and Corona Lines were built to IRT specifications, whose platforms were too wide for BMT rolling stock.

As a result, those trains terminated at Queensboro Plaza using a relay track east of the station to reverse direction for the return trip to Manhattan.

[13] Since then, the Astoria Line has hosted the northern end of various services running from Brooklyn through Manhattan; see B, N, Q, R, T and W for details.

The MTA also considered an eastward extension along Ditmars Boulevard, and a plan to reroute LaGuardia-bound trains from Queensboro Plaza through the Sunnyside rail yard and along the eastern edge of St. Michael’s Cemetery to elevated tracks parallel to the Grand Central Parkway.

[25] Community opposition was strong and therefore the plan was canceled in July 2003;[26][27] however, as of 2021[update], it is being reconsidered after New York governor Kathy Hochul requested the Port Authority find alternatives to the AirTrain LaGuardia project.

[28] The Regional Plan Association, in its Fourth Plan in 2017, anticipated that the population of Astoria would quickly grow over the next three decades, and so called for the Astoria Line to be extended to a new storage yard at Ditmars Boulevard and 20th Street, which would provide added capacity.

In addition, a new station at 21st Avenue and 20th Street would improve access for the currently underserved but dense northwest parts of Astoria.