and AA service began on September 10, 1932 with the opening of the IND Eighth Avenue Line. The Independent Subway System used single letters to refer to express services and double letters for local services. The ran express and the AA ran local, from 168th Street to Chambers Street/World Trade Center, known at the time as Hudson Terminal. The AA ran at all times, and it was extended to 207th Street during nights and on Sundays when the did not run. When the Eighth Avenue Line was extended to Jay Street–Borough Hall on February 1, 1933 the AA was extended there, but only during the times when the didn't run; it continued to terminate at Chambers Street when the did run. On July 1, 1933, the AA was suspended when the Concourse Line opened and the new service provided local service on Eighth Avenue in its place. The AA was suspended until the IND Sixth Avenue Line opened on December 15, 1940. The AA only ran during non-rush hours and Saturday late afternoon through all day Sunday service to Chambers Street. Rush hours, which at the time included Saturday mornings and afternoons, the AA did not run; it was replaced by the BB service, which instead ran on the Sixth Avenue Line. This pattern was unchanged until August 28, 1977, when late night service was replaced by an all local service.
Service as the K
On May 6, 1985, as part of the elimination of double letters, the AA was renamed the K. This service operated between 168th Street and World Trade Center during midday, evenings, and weekends. During late night hours, the A express made local stops on the Eighth Avenue Line. During rush hours, the, formerly the, ran between Bedford Park Boulevard and Rockaway Park–Beach 116th Street, replacing the K as the local on Eighth Avenue. This change was not officially reflected in schedules until May 24, 1987. On December 11, 1988, as part of the widespread service changes that day, the K was discontinued, being replaced by the train, which was expanded from its rush-hour only service to include midday service between 145th Street and Euclid Avenue, early evening service from 145th Street to World Trade Center, and weekend service matching the former K between 168th Street and World Trade Center. The was also expanded to middays to match part of the former K.
Final route
Service pattern
The following table shows the lines used by the K service:
Line
From
To
Tracks
IND Eighth Avenue Line
168th Street
World Trade Center
Local
Stations
For a more detailed station listing, see the articles on the lines listed above.