Unused New York City Subway service labels
The New York City Subway currently uses various letters and numbers to designate the routes that trains use over the differing lines in the system. Along with the color corresponding to the route's trunk line, these form a unique identifier for the route, easing navigation through the complex system. Several service labels have either been phased out or never been used. This list covers the labels not used as of March 2013.
A Division numbers 
The A Division uses single-digit numbers for each route. 1 through 7 are in use.
- 0 is used as the internal designation of the 42nd Street Shuttle.
- 8 has been used in the past for various routes, most recently the Bronx portion of the Third Avenue El, ended in 1973.
- 9 was used for skip-stop service on the IRT Broadway – Seventh Avenue Line from 1989 to 2005. It was also used as the designator for the IRT Dyre Avenue Line shuttle between 1941 and 1966.
Two-digit numbers have never been used by the A Division, but have been seen on the current rollsigns of some trains, paired with colors used with other services. It is likely that these were assigned arbitrarily, for use if the MTA changed the additional rush hour express service designators from a "diamond" version of the regular number to a separate number.
B Division letters 
Trains of the B Division use single letters of the English alphabet. These service letters are unused as of January 2011, but some have been used or proposed for services at various points in time:
- H was last used publicly for the Rockaway Park Shuttle in 1993, but is still used as its internal-only designator by NYC Transit. Since November 2012, the letter returned for a fare-free shuttle service in the Rockaways after damage caused by Hurricane Sandy rendered normal A train service in the area inoperable; however, this service is temporary and will only last until A train services to the Rockaways are restored.
- I has never been used due to its visual similarity to the number 1.
- K has been used for multiple routes in the past, most recently as an Eighth Avenue Line train (discontinued in 1988).
- O has never been used due to its visual similarity to the number 0.
- P (short for Penn Station) was planned for a nonstop between Sutphin Boulevard – Archer Ave (at the LIRR's Jamaica station) and 34th Street – Penn Station, continuing locally to 168th Street, via the BMT Archer Avenue Line, BMT Jamaica Line, Chrystie Street Connection, IND Sixth Avenue Line and IND Eighth Avenue Line (switching to the latter at West Fourth Street) in the 1990s. This would have been used during a threatened Amtrak strike that would have prevented LIRR trains from entering Penn Station.
- T was used for BMT West End Line services, but was quickly replaced by the expanded B service after services were reorganized following the opening of the Chrystie Street Connection. T is the planned label for the new Second Avenue Line.
- U has never been used, as it sounds like the word "you".
- V was introduced in 2001 for weekday local service on the IND Queens Boulevard Line and IND Sixth Avenue Line via 53rd Street, after the F was shifted to the newly-opened IND 63rd Street Line. V service was discontinued in 2010 due to budgetary concerns, replaced almost entirely by a rerouted M train.
- W was introduced in 2001 for BMT West End Line—BMT Broadway Line service via the south side of the Manhattan Bridge; reconstruction of the bridge's north tracks prevented the usual B service from running to the West End Line. After work was completed, the W became a weekday local service on the BMT Broadway Line and BMT Astoria Line, supplementing the N in Queens and the R in Manhattan. This service was discontinued in 2010 due to budgetary concerns, replaced by the N and Q in Queens and the N and R in Manhattan.
- X is used as a placeholder for subway lines under construction.
- Y has never been used, as it sounds like the word "why".
- The JFK Express bullet, featuring an airplane inside a blue circle, was used from 1978 until 1990.
Prior to 1985, the B Division used two-letter combinations to indicate differing variations of similar services, but these were phased out in favor of single-letter designators. These former service names are covered in their corresponding current letters.
- MTA's tweet on partially restoring the Rockaway shuttle
- Hurricane Sandy Recovery Service As of November 20
- Beginning Tuesday, Fare-Free H Shuttle Replaces Portion of A Line in Rockaways
- V and W Trains join a long list of routes that have bowed out of the Subways, AM New York. Accessed 2010-08-21
- Ritea, Steve (2008-01-10). "LIRR preps for strike that might shut Penn Station". Newsday. Retrieved 2009-09-26.
- "Major Subway Changes Set for Monday". Metropolitan Transportation Authority. June 24, 2010. Retrieved December 24, 2010.
See also