View source for New York City Subway nomenclature

{{Short description|Terminology of the New York City Subway}}
{{Use American English|date=February 2025}}
{{Multiple issues|
{{More citations needed|date=March 2023}}
{{Original research|date=July 2025|reason=Large parts of the article consist of unsourceable information.}}}}
{{Use mdy dates|date=July 2025}}
[[File:InsideStation.JPG|thumb|300px|Signs for southbound ("Downtown & Brooklyn") and northbound ("Uptown & The Bronx") platforms at the [[59th Street – Columbus Circle (New York City Subway)|59th Street – Columbus Circle]] station]]
{{New York City Subway sidebar}}
'''New York City Subway nomenclature''' is the terminology used in the [[New York City Subway]] system. The modern system was constructed and operated by multiple companies, which were unified into a single system in 1940. The process of integrating multiple systems, as well as over a century of service changes, have led to a complexity of conventions around station naming, directionality and the routes themselves. In particular, the New York City Subway distinguishes between ''[[List of New York City Subway lines|line]]s'', or individual sections of subway, and ''[[List of New York City Subway services|service]]s'', or train routes. Services are represented visually by grouped, color coded ''service bullets'', which have changed significantly over time.{{TOC limit|4}}

==Current usage==
[[File:R68A 5092.jpg|thumb|left|205px|A rollsign reading on an [[R68A (New York City Subway car)|R68A]] car. The sign reads:
{| style="margin:auto"
|{{rint|newyork|q|size=60}} || style="text-align:center" | [[57th Street – Seventh Avenue (BMT Broadway Line)|Midtown<br>57 St/7 Av]]<br>
----
[[Coney Island – Stillwell Avenue (BMT Brighton Line)|Coney Island]]
|}]]
Each section of the subway has three identifying characteristics, ''line'', ''service'' and ''color''.

=== Subway lines ===
Sections of the physical infrastructure of the subway system are called ''lines'' and are identified by their name and frequently their original operating company or division: [[Brooklyn–Manhattan Transit Corporation]] (BMT), [[Interborough Rapid Transit Company]] (IRT), [[Independent Subway System]] (IND). For example, the line under [[Eighth Avenue (Manhattan)|Eighth Avenue]] is called the [[IND Eighth Avenue Line]]. With few exceptions, these names have remained relatively constant throughout the history of the subway.

Public usage of the line names varies widely, although the MTA's public usage of trunk names has increased since 2012, especially on [[Technology of the New York City Subway#FASTRACK|Fastrack]] signs. Internally, the [[Metropolitan Transportation Authority|MTA]] also uses the names, both for legal reasons and to describe lines, services and locations without ambiguity. Although the three major subway systems are now unified, the terms BMT, IRT and IND are still used in line, structure and building descriptions and capital contract specifications. However, the names of the former companies are no longer used by much of the general public.<ref>{{cite news | last=Sims | first=Calvin | title=About New York; Alphabet Soup: Telling an IRT From a BMT | work=The New York Times | date=June 30, 1990 | url=https://www.nytimes.com/1990/06/30/nyregion/about-new-york-alphabet-soup-telling-an-irt-from-a-bmt.html | access-date=January 21, 2018}}</ref>

=== Service designations ===
Each operating ''service'' or ''route'' is assigned a letter or number. This is a path that the train service uses along the various ''lines''. These are the most familiar names among the public, but may change due to construction or reroutes. Former [[Interborough Rapid Transit Company|IRT]] services (now known as ''[[A Division (New York City Subway)|A Division]]'') are assigned numbers, and former [[Brooklyn–Manhattan Transit Corporation|BMT]] and [[Independent Subway System|IND]] services (now known as ''[[B Division (New York City Subway)|B Division]]'') are assigned letters.

Prior to consolidation under city ownership in 1940, the BMT routes were also assigned numbers. As track connections were built between IND and BMT lines to create a unified division, the BMT routes were gradually assigned letters for consistency with the IND naming scheme. IRT trains and tunnels are narrower, however, so the two divisions do not mix in revenue service.

=== Colors and service bullets ===
Each service is also assigned a ''color''. Since 1979, each service's color corresponds to the line that service primarily uses below 60th Street in [[Manhattan]]. In the case of the [[IND Crosstown Line]] (which never enters Manhattan), the color is {{NYCS const|color|lightgreen}}. This is defined as the ''trunk line''. [[S (New York City Subway service)|All shuttle services]] are {{NYCS const|color|darkgray}}.<ref name="Hertz-Gothamist">{{cite web|title=Michael Hertz, Designer of the NYC Subway Map|url=http://gothamist.com/2007/08/03/michael_hertz_d.php|last=Hogarty|first=Dave|date=August 3, 2007|work=[[Gothamist]]|access-date=July 4, 2009|archive-date=August 18, 2009|archive-url=https://web.archive.org/web/20090818012400/http://gothamist.com/2007/08/03/michael_hertz_d.php|url-status=dead}}</ref> The list of trunk lines and colors is shown in the following table.

<div align=center>
{{NYCS const/table|style=margin:0 0 0 0}}
</div>
==== Diamond services ====
[[File:NYCS-line-black-Flushing.svg|frame|right|Normal and diamond [[7 (New York City Subway service)|7]] bullets]]
Despite its efforts toward single identifiers for each service, the MTA uses diamond bullets to distinguish rush-hour express service from regular service, which is represented with circular bullets.  Since a route letter or number is ordinarily presented inside a circle, variants of the same service are shown as the same letter or number inside a diamond shape.

=====In use=====
* ''[[6 (New York City Subway service)|6]]'' regular service operates local at all times; weekday peak-direction ''&lt;6&gt;'' diamond service runs express in the Bronx (with local service in the same direction cut back to [[Parkchester (IRT Pelham Line)|Parkchester]]).
* ''[[7 (New York City Subway service)|7]]'' regular service operates local at all times; weekday [[Rush hour|rush-hour]] peak-direction ''&lt;7&gt;'' diamond service runs express in Queens.
* ''[[F (New York City Subway service)|F]]'' regular service operates at all times; weekday [[Rush hour|rush-hour]] peak-direction ''&lt;F&gt;'' diamond service runs express in Brooklyn.

=====Former use=====
Until May 2005, rush hour ''[[5 (New York City Subway service)|5]]'' service to [[Nereid Avenue (IRT White Plains Road Line)|Nereid Avenue–238th Street]] in the Bronx was marked with a diamond with regular "circle" service to [[Eastchester–Dyre Avenue (IRT Dyre Avenue Line)|Eastchester–Dyre Avenue]]. Both services were express services in the Bronx between [[East 180th Street (IRT White Plains Road Line)|East 180th Street]] and [[Third Avenue–149th Street (IRT White Plains Road Line)|Third Avenue–149th Street]] during rush hours in peak direction.

Diamond service operated on the [[BMT Brighton Line]] while the north side of the [[Manhattan Bridge]] was closed for repairs from 2001 to 2004. Full-time local service was designated with a circle ''[[Q (New York City Subway service)|Q]]'' while weekday-only express service was designated with a diamond ''&lt;Q&gt;''.<ref name="feb2004map">[[New York City Transit Authority]], {{cite web |title=MTA New York City Subway with bus, railroad, and ferry connections |url=http://www.mta.info/nyct/maps/subwaymap.pdf |url-status=dead |archive-url=https://web.archive.org/web/20040326024754/http://www.mta.info/nyct/maps/subwaymap.pdf |archive-date=March 26, 2004 |website=mta.info}}&nbsp;{{small|(802&nbsp;KB)}}, February 2004</ref> Other services have also used the diamond before and during the closure from 1986 to 2004; at least one (a brown ''&lt;[[R (New York City Subway service)|R]]&gt;'') dated from a [[Brooklyn–Manhattan Transit Corporation|BMT]] special service using the same number ([[BMT 2]]) as the main service that became the ''R'' from 1986 to 1988.

In addition to the ''&lt;5&gt;'', ''&lt;6&gt;'', and ''&lt;7&gt;'', official maps and schedules used to show several other rush-hour only services with a diamond, including the ''[[4 (New York City Subway service)|&lt;4&gt;]]'' bypassing [[138th Street (IRT Jerome Avenue Line)|138th Street]],<!--not on schedules--> ''[[A (New York City Subway service)|&lt;A&gt;]]'' to [[Rockaway Park–Beach 116th Street (IND Rockaway Line)|Rockaway Park]],<ref>[[New York City Transit Authority]], {{cite web |title=A Train Timetable: Far Rockaway or Lefferts Blvd, Queens, and 59 St, Manhattan |url=http://mta.info/nyct/service/pdf/ttcur.pdf |url-status=dead |archive-url=https://web.archive.org/web/20040219025932/http://mta.info/nyct/service/pdf/ttcur.pdf |archive-date=February 19, 2004}}&nbsp;{{small|(151&nbsp;KB)}}, effective fall 2003</ref> ''[[B (New York City Subway service)|&lt;B&gt;]]'' and ''[[C (New York City Subway service)|&lt;C&gt;]]'' to [[Bedford Park Boulevard (IND Concourse Line)|Bedford Park Boulevard]],<ref>[[New York City Transit Authority]], {{cite web |title=B/D/S Manhattan Bridge Service Change Train Timetable |url=http://mta.info/nyct/service/pdf/tdcur.pdf |url-status=dead |archive-url=https://web.archive.org/web/20030629092241/http://mta.info/nyct/service/pdf/tdcur.pdf |archive-date=June 29, 2003}}&nbsp;{{small|(98.4&nbsp;KB)}}, effective April 2003</ref><!--not on the February 22, 2004 schedule though--> ''[[D (New York City Subway service)|&lt;D&gt;]]'' express on the [[IND Concourse Line]],<!--not on schedules--> and the ''[[M (New York City Subway service)|&lt;M&gt;]]'' to [[Bay Parkway (BMT West End Line)|Bay Parkway]].<ref>[[New York City Transit Authority]], {{cite web |title=M Train Timetable |url=http://mta.info/nyct/service/pdf/tmcur.pdf |url-status=dead |archive-url=https://web.archive.org/web/20030607111302/http://mta.info/nyct/service/pdf/tmcur.pdf |archive-date=June 7, 2003}}&nbsp;{{small|(73.3&nbsp;KB)}}, effective April 2003</ref> In May 2004, the map was changed to show only the diamond ''&lt;6&gt;'' and ''&lt;7&gt;''.<ref name="feb2004map" /><ref>[[New York City Transit Authority]], {{cite web |title=MTA New York City Subway with bus, railroad, and ferry connections |url=http://mta.info/nyct/maps/subwaymap.pdf |url-status=dead |archive-url=https://web.archive.org/web/20041106081012/http://mta.info/nyct/maps/subwaymap.pdf |archive-date=November 6, 2004}}&nbsp;{{small|(790&nbsp;KB)}}, May 2004</ref> The diamond symbol usage has thus been redefined to indicate a variant rush-hour express service running simultaneously with a local service in the same direction.

====Special services====
[[File:SpecialIMG 3939R46.jpg|thumb|220px|An [[R46 (New York City Subway car)|R46]] LCD sign on the [[IND Sixth Avenue Line]]]]
''Special'' is a signifier for a train that is running along a nonstandard route. It is sometimes used for special holiday trains,<ref>{{cite web |date=November 25, 2012 |title=Chambers Special – vintage subway train new york city sign |url=https://www.flickr.com/photos/59949757@N06/8218548227 |website=flickr}}</ref><ref>{{cite web |date=December 21, 2013 |title=All Aboard the Holiday Train |url=https://shershegoes.com/aboard-holiday-train/ |website=shershegoes.com}}</ref> baseball game service,<ref>{{cite web |last=Dj Hammers |date=May 13, 2016 |title=Yankees Baseball Special Train Action |url=https://www.youtube.com/watch?v=Y50l6zBYmUQ |url-status=live |archive-url=https://ghostarchive.org/varchive/youtube/20211212/Y50l6zBYmUQ |archive-date=December 12, 2021 |website=YouTube}}{{cbignore}}</ref> or for emergency or custom routes. Most trains have a "Special" option on the rollsigns or LCD/LED displays.<ref>{{Cite web |title=Complete NY NYC Subway Roll Sign R27/30 Front Route Color 1984 a C F Train Decor • $1,499.00 |url=https://picclick.com/Nyc-Subway-R27-Train-Roll-Sign-Special-Collectible-401301464373.html}}</ref>

===Station names===
[[File:Howard Beach-JFK Sign.JPG|thumb|right|upright=1.2|alt=Station sign at the Howard Beach-JFK Airport station in Queens|The name of the [[Howard Beach–JFK Airport (IND Rockaway Line)|Howard Beach–JFK Airport]] station in [[Queens]] bears the neighborhood's name of [[Howard Beach, Queens|Howard Beach]], as well as advertises its connection to [[John F. Kennedy International Airport]] via the "[[AirTrain JFK|AirTrain to JFK]]."]]
Stations usually bear the [[street name]]s of streets the line crosses, but may also be named after neighborhoods or prominent locations (e.g., "[[Brighton Beach (BMT Brighton Line)|Brighton Beach]]" for [[Brighton Beach]]; "[[Cypress Hills (BMT Jamaica Line)|Cypress Hills]]" for [[Cypress Hills, Brooklyn]]) or combinations of these (e.g., "[[Times Square–42nd Street (New York City Subway)|Times Square–42nd Street]]" for [[Times Square]] and [[42nd Street (Manhattan)|42nd Street]]; "[[Astoria–Ditmars Boulevard (BMT Astoria Line)|Astoria–Ditmars Boulevard]]" for [[Astoria, Queens|Astoria]] and [[Ditmars Boulevard]]), especially at line terminals. Others are named after major destinations, either along with the street names (e.g., "[[68th Street–Hunter College (IRT Lexington Avenue Line)|68th Street–Hunter College]]" for [[Hunter College]], "[[81st Street–Museum of Natural History (IND Eighth Avenue Line)|81st Street–Museum of Natural History]]" for [[American Museum of Natural History]]) or in some cases without (e.g., "[[Pelham Bay Park (IRT Pelham Line)|Pelham Bay Park]]" for [[Pelham Bay Park]], "[[Borough Hall (IRT Broadway–Seventh Avenue Line)|Borough Hall]]" for [[Brooklyn Borough Hall]]). When a station is served by trains of multiple trunk lines, the names used on each line may be hyphenated to form a station name that refers to an intersection (e.g., [[Fourth Avenue/Ninth Street station|Fourth Avenue–Ninth Street]]; [[Myrtle–Wyckoff Avenues station|Myrtle–Wyckoff Avenues]]). Of the system's {{NYCS const|number|total}} stations, more than 300 are named after streets or street intersections alone, while the remainder are identified by different combinations of streets, neighborhoods and landmarks.<ref name=":0">{{Cite web |title={{!}} State of New York |url=https://data.ny.gov/d/39hk-dx4f/visualization |access-date=June 6, 2025 |website=data.ny.gov}}</ref>

[[List of New York City Subway stations#Stations with the same name|Many stations share names]], so to uniquely identify a station, the line name or cross street must be specified: for example, there are three stations named [[Kings Highway (disambiguation)#Railway stations|Kings Highway]] in [[Brooklyn]].<ref name=":0" /> Usually, identifying the service is also sufficient (e.g., "[[Kings Highway (BMT Brighton Line)|Kings Highway]] on the [[B (New York City Subway service)|B]] and [[Q (New York City Subway service)|Q]]" to denote the station at East 16th Street), but as services are transient, this is not a permanent label.

The MTA has looked at certain station names as a source of revenue. In June 2009, the Atlantic Avenue/Pacific Street station in Brooklyn was renamed [[Atlantic Avenue–Barclays Center station|Atlantic Avenue–Barclays Center]] following a deal with [[Forest City Ratner]] who pay [[U.S. dollar|$]]200,000 per year for the rights to the name.<ref>{{cite news |first=Michael M. |last=Grynbaum |title=M.T.A. Sells Naming Rights to Subway Station |url=https://www.nytimes.com/2009/06/24/nyregion/24naming.html?ref=todayspaper |work=[[The New York Times]] |date=June 23, 2009 |access-date=September 21, 2020 }}</ref> On the other hand, Willets Point–Shea Stadium was renamed [[Mets–Willets Point station (IRT Flushing Line)|Mets–Willets Point]] because the MTA could not reach a deal with the [[New York Mets|Mets organization]].<ref>{{cite web | last=Neuman | first=William | title=Mets Decline to Buy Name for Subway Station at Citi Field | website=The New York Times | date=March 11, 2009 | url=https://www.nytimes.com/2009/03/12/nyregion/12shea.html | access-date=October 24, 2015}}</ref> Had the naming rights deal been achieved, the station would have been known as Willets Point–Citi Field.<ref>{{cite news |title=Stadium Is Citi Field, but the Subway Stop Has Other Ideas |first=William |last=Neuman |url=https://www.nytimes.com/2009/03/12/nyregion/12shea.html |newspaper=The New York Times |date=March 11, 2009 |access-date=September 21, 2020}}</ref>

=== Describing directions ===

==== Public information ====
On the [[Brooklyn–Manhattan Transit Corporation|BMT]] system, most in-station signage specified ''to city'' and ''from city''. Currently signs typically read ''to Manhattan'', if the train is heading toward Manhattan, and ''to destination'' (e.g. ''to Coney Island'' or ''to Canarsie''), if the train is heading toward an outer-borough destination. If the train is headed to a different borough, it may also be described as ''borough-bound'' (e.g. ''Manhattan-bound'' or ''Brooklyn-bound''). If its terminus is in the same borough, it will be described as ''terminus-bound'', for example, ''Eighth Avenue-bound'' or ''Rockaway Parkway-bound''. In [[Manhattan]] or the [[Bronx]], directions may be described as ''uptown'' and ''downtown'', roughly corresponding to compass north and south. If the final destination is more than one borough away, signs will generally display the name of the next one or two boroughs that the route will pass through. Trains would display ''to Uptown'' and ''Borough'' if the train is heading uptown and into another borough, or ''to Downtown'' and ''Borough'' if the train is heading downtown and into another borough.

==== Internal usage<!-- I am not sure what the inclusion of this was meant to accomplish - perhaps someone else could do a better job of rephrasing this and adding citations.  --> ====
In the United States, most railroads have only two [[rail directions]]. In this vein, all New York City subway lines are deemed to run north–south. In many cases, this is close to the related compass direction, but this is not always possible. Any line that enters Manhattan from the Bronx or Queens heads south into Manhattan; any line entering Manhattan from Brooklyn goes north into Manhattan, with the [[BMT Nassau Street Line]] and [[BMT Canarsie Line]]s being the only exception, as the Nassau Street Line heads further south into Manhattan's Financial District after entering Manhattan over the [[Williamsburg Bridge]], and the Canarsie Line goes neither north nor south. Directions of other lines are determined by following the services that run over them; except for the [[Brooklyn–Manhattan Transit Corporation|BMT]] Eastern Division services (over the [[Williamsburg Bridge]]), which change direction at [[Brooklyn Bridge–City Hall/Chambers Street (New York City Subway)#BMT Nassau Street Line platforms|Chambers Street]], every service has one north end and one south end. On the [[42nd Street Shuttle]], railroad north is compass west, due to the line's former status as part of the main line.

==History==
This nomenclature has been complicated by the differing systems and cultures of the former private companies that operated parts of the system, by the need for non-ambiguous names in a city where there are [[List of New York City Subway stations#Stations with the same name|stations with the same name]] on different lines in different locations and even different [[Political subdivisions of New York State#Borough|boroughs]], and by changing perceptions of the best way to communicate information to a diverse public.

Up until 1940, there were three major operators of New York subway and elevated lines, the privately owned [[Brooklyn–Manhattan Transit Corporation]] (BMT), the privately owned [[Interborough Rapid Transit Company]] (IRT) and the municipally owned [[Independent Subway System]] (ISS or ICOS before 1940, now IND).

Service labels have always been assigned based on their outer-borough line (Brooklyn on the BMT, Bronx on the IRT and IND) and then by the Manhattan trunk if necessary to distinguish multiple services on the same line.

===BMT===
{| class="wikitable" style="float: right; margin: 0 0 1em 1em; width: 40%;"
|+ BMT numbers, 1924–1967
|-
!
! Pre-1967 service designation
! 1967 service designation
! Line Name
! Current service designation
! Division
|-
! [[BMT 1|1]]
| Q QB QT
| D QB QJ
| [[BMT Brighton Line|Brighton Beach Line]]
| {{NYCS Brighton}}
| rowspan=4 | Southern Division (subway)
|-
! [[BMT 2|2]]
| N RR T TT
| B N RJ RR
| [[BMT Fourth Avenue Line|Fourth Avenue (Brooklyn) Line]]
| {{NYCS Fourth}}
|-
! [[BMT 3|3]]
| T TT
| B
| [[BMT West End Line|West End Line]]
| {{NYCS West End}}
|-
! [[BMT 4|4]]
| N
| N NX
| [[BMT Sea Beach Line|Sea Beach Line]]
| {{NYCS Sea Beach}}
|-
! [[BMT 5|5]]
| D Culver Shuttle
| F [[Culver Shuttle|SS]]
| [[IND Culver Line|Culver Line]]
| {{NYCS Culver IND south}}
| rowspan=3 | Southern Division (elevated)
|-
! [[BMT 6|6]]
|
|
| [[BMT Fifth Avenue Line|Fifth Avenue–Bay Ridge Line]]
|
|-
! [[BMT 7|7]]
| Franklin Shuttle
| [[Franklin Avenue Shuttle|SS]]
| [[BMT Franklin Avenue Line|Brighton–Franklin Line]]
| {{NYCS Franklin}}
|-
! [[BMT 8|8]]
| QB QT T
| RR
| [[BMT Astoria Line|Astoria Line]]
| {{NYCS Astoria}}
| rowspan=2 | Queens Division (elevated)
|-
! [[BMT 9|9]]
|
|
| [[IRT Flushing Line|Flushing Line]]
| {{NYCS Flushing}}
|-
! [[BMT 10|10]]
|
| {{NYCS Myrtle}}
| [[BMT Myrtle Avenue Line|Myrtle Avenue–Chambers Street Line]]
| {{NYCS|M}}
| rowspan=6 | Eastern Division (elevated)
|-
! [[BMT 11|11]]
|
| [[MJ (New York City Subway service)|MJ]]
| [[BMT Myrtle Avenue Line|Myrtle Avenue Line]]
| {{NYCS|M}}
|-
! [[BMT 12|12]]
|
|
| [[BMT Lexington Avenue Line|Lexington Avenue Line]]
|
|-
! [[BMT 13|13]]
|
|
| [[BMT Fulton Street Line|Fulton Street Line]]
| {{NYCS Fulton east}}{{refn|The IND Fulton Street Subway partially replaced the BMT Fulton Street El after unification. The A service uses the same route as the 13 from 80th Street to Lefferts Boulevard in Queens; the current Fulton Street Line is neither part of the Eastern Division nor connected to it.}}
|-
! [[BMT 14|14]]
|
| JJ KK M QJ RJ
| [[BMT Jamaica Line|Broadway (Brooklyn) Line]]
| {{NYCS Jamaica west}}
|-
! [[BMT 15|15]]
|
| JJ KK QJ RJ
| [[BMT Jamaica Line|Jamaica Line]]
| {{NYCS Jamaica east}}
|-
! [[BMT 16|16]]
|
| LL
| [[BMT Canarsie Line|14th Street–Canarsie Line]]
| {{NYCS Canarsie}}
| Eastern Division (subway)
|}
[[File:R1 BMT 5.gif|thumb|100px|left|Typical pre-1967 BMT [[rollsign]] number]]
The [[Brooklyn–Manhattan Transit Corporation|BMT]] was the inheritor of subway, elevated and surface [[rapid transit]] lines that had been built in Brooklyn and Queens by a variety of previous operators.<ref>{{Cite book |last=Commission |first=New York (State) Transit |url=https://books.google.com/books?id=lFxLAQAAMAAJ&pg=PA501 |title=Annual Report |date=1924 |publisher=J.B. Lyon Company, printers |language=en}}</ref> The BMT identified most of its lines by the common names given to them, which often dated back into the 19th century. Services on these lines usually had the same name as the line itself: for example, on the [[IND Culver Line|Culver Line]], trains were signed ''Culver Local'' or ''Culver Express''.

Partly as a result of its steam railroad history, BMT terminals were much more frequently named after neighborhoods or towns rather than streets, so trains were signed for ''Coney Island'', ''Canarsie'' and ''Jamaica'' rather than ''Stillwell Avenue'', ''Rockaway Parkway'' and ''168th Street''. Stations also tended to use local names, but this gradually changed as lines were upgraded, so that stations like [[Bath Junction]] on the [[BMT Sea Beach Line|Sea Beach Line]] became ''New Utrecht Avenue'' and [[Manhattan Terrace]] on the [[BMT Brighton Line|Brighton Line]] became ''Avenue J''.

The BMT introduced numbers for all its services in 1924 but these were originally mostly for map purposes. The first train cars to display the numbers on the front of the train were [[D-type Triplex (New York City Subway car)|D-type Triplex]] cars, which were introduced as prototypes in 1925, and then in production in 1927, and these only on the front of the trains.<ref>{{cite web|url=http://www.nycsubway.org/perl/show?3033|title=Showing Image 3033|work=nycsubway.org}}</ref> In 1931 these numbers were also used on 20 IND [[R1 (New York City Subway car)|R1]]  cars when they were tested by the City on BMT lines, and also on 140 of these cars from 1949 to 1955 while in BMT service as well.
{{-}}

===IRT===
{| class="wikitable" style="float: right; margin: 0 0 1em 1em; width: 40%"
|+ Early IRT numbers
!
! Uptown branch
! Manhattan trunk line
|-
| [[1 (New York City Subway service)|1]]
| [[IRT Broadway–Seventh Avenue Line|Broadway–Seventh Avenue Line]]
| rowspan=3 | [[IRT Broadway–Seventh Avenue Line|Broadway–Seventh Avenue Line]]
|-
| [[2 (New York City Subway service)|2]]
| [[IRT White Plains Road Line|White Plains Road Line]]
|-
| [[3 (New York City Subway service)|3]]
| [[IRT Lenox Avenue Line|Lenox Avenue Line]]
|-
| [[4 (New York City Subway service)|4]]
| [[IRT Jerome Avenue Line|Jerome Avenue Line]]
| rowspan=3 | [[IRT Lexington Avenue Line|Lexington Avenue Line]]
|-
| [[5 (New York City Subway service)|5]]
| [[IRT White Plains Road Line|White Plains Road Line]]
|-
| [[6 (New York City Subway service)|6]]
| [[IRT Pelham Line|Pelham Line]]
|-
| [[7 (New York City Subway service)|7]]
| [[IRT Flushing Line|Flushing Line]]
| rowspan=2 | [[Queensborough Line]]
|-
| [[8 (New York City Subway service)|8]]{{refn|IRT 8 trains traveled between Manhattan and Astoria (this service was not labeled as such until 1948). A similar service operated by the BMT, also numbered 8, traveled only from Astoria to Queensboro Plaza. Both services were discontinued in 1949.<ref>{{Cite web|date=1949|title=Notice To Passengers|url=https://www.flickr.com/photos/127872292@N06/50064959821/in/dateposted/|access-date=July 6, 2020|website=Flickr|publisher=New York City Board of Transportation}}</ref>}}
| [[BMT Astoria Line|Astoria Line]]
|-
| [[9 (New York City Subway service)|9]]{{refn|Label used until 1967.<ref>{{Cite web|date=November 1967|title=Rapid Transit Guide|url=https://www.flickr.com/photos/127872292@N06/24936413491/in/album-72157652636594213/|access-date=June 19, 2020|website=Flickr|publisher=New York City Transit Authority}}</ref>}}
| colspan=2 | [[IRT Dyre Avenue Line|Dyre Avenue Shuttle]] (non-Manhattan service)
|}
[[File:R12 IRT 5.gif|thumb|100px|left|Typical pre-1967 IRT [[rollsign]] number]]
The [[Interborough Rapid Transit Company|IRT]] was the contractor with the [[New York City|City of New York]] to operate the [[Early history of the IRT subway|first subway line]]; by that time it was already leasing all the [[elevated railway]]s in Manhattan. Unlike the BMT, the IRT had multiple long mainlines from which several branch lines extended into the [[Bronx]], [[Queens]] and [[Brooklyn]]. The IRT therefore named their services for these mainlines rather than their branches. The branch lines were referred to on the destination signs instead, so that typical signage read ''Lexington Avenue Express'' to ''Woodlawn&nbsp;— Jerome'' or ''Utica Avenue&nbsp;— Brooklyn'', meaning Woodlawn on the Jerome Avenue Line and Utica Avenue on the Brooklyn Line. Where a service ended in downtown [[Manhattan]], it simply carried the destination name, for example ''South Ferry'' or ''Chatham Square''.

The IRT routes were given numbered designations in 1948 with the introduction of [[List of New York City Subway R-type contracts|"R-type" rolling stock]], which contained [[rollsign]]s with numbered designations for each service.<ref>{{cite web | last=Brown | first=Nicole | title=How did the MTA subway lines get their letter or number? NYCurious | website=amNewYork | date=May 17, 2019 | url=https://www.amny.com/transit/nyc-subway-name-1-31116195/ | access-date=January 27, 2021 | archive-date=March 2, 2021 | archive-url=https://web.archive.org/web/20210302020704/https://www.amny.com/transit/nyc-subway-name-1-31116195/ | url-status=live }}</ref> The routes on the [[IRT Broadway–Seventh Avenue Line]] were given the designations {{NYCS|1}}, {{NYCS|2}}, and {{NYCS|3}}, while the routes on the [[IRT Lexington Avenue Line]] were given the designation {{NYCS|4}}, {{NYCS|5}}, and {{NYCS|6}}, The [[IRT Flushing Line]] received the designation {{NYCS|7}}, and the Bronx section of the [[IRT Third Avenue Line]] was given the designation {{NYCS|8}}. The designation {{NYCS|9}} was assigned to trains on the [[IRT Dyre Avenue Line]], which at the time was a shuttle service; the [[Bowling Green Shuttle]] and [[42nd Street Shuttle]] did not receive numbers.<ref>{{cite magazine|last1=Friedlander|first1=Alex|last2=Lonto|first2=Arthur|last3=Raudenbush|first3=Henry|date=April 1960|title=A Summary of Services on the IRT Division, NYCTA|url=https://erausa.org/pdf/bulletin/1960/1960-01-bulletin.pdf|journal=New York Division Bulletin|publisher=Electric Railroaders' Association|volume=3|issue=1|pages=2–3|access-date=January 27, 2021|archive-date=September 14, 2020|archive-url=https://web.archive.org/web/20200914232631/https://erausa.org/pdf/bulletin/1960/1960-01-bulletin.pdf|url-status=dead}}</ref>
{{-}}

===IND===
{| class="wikitable" style="float: right; margin: 0 0 1em 1em; width: 40%"
|+ Early IND letters
!
! Uptown branch
! Manhattan trunk line
|-
| [[A (New York City Subway service)|A]]
| rowspan=2 | [[IND Eighth Avenue Line|Washington Heights Line]]
| [[IND Eighth Avenue Line|Eighth Avenue Line]]
|-
| [[B (New York City Subway service)|B]]
| [[IND Sixth Avenue Line|Sixth Avenue Line]]
|-
| [[C (New York City Subway service)|C]]
| rowspan=2 | [[IND Concourse Line|Concourse Line]]
| [[IND Eighth Avenue Line|Eighth Avenue Line]]
|-
| [[D (New York City Subway service)|D]]
| [[IND Sixth Avenue Line|Sixth Avenue Line]]
|-
| [[E (New York City Subway service)|E]]
| rowspan=2 | [[IND Queens Boulevard Line|Queens Boulevard Line]]
| [[IND Eighth Avenue Line|Eighth Avenue Line]]
|-
| [[F (New York City Subway service)|F]]
| [[IND Sixth Avenue Line|Sixth Avenue Line]]
|-
| [[G (New York City Subway service)|G]]
| colspan=2 | [[IND Crosstown Line|Brooklyn–Queens Crosstown Line]] (non-Manhattan service)
|-
| [[H (New York City Subway service)|H]]
| colspan=2 | [[IND Fulton Street Line|Fulton Street Line]] (non-Manhattan service)
|-
| [[S (New York City Subway service)#Former uses|S]]
| colspan=2 | Specials (no consistent usage)
|}
[[File:R1 IND CC.gif|thumb|100px|left|Typical pre-1967 IND [[rollsign]] letter]]
The [[Independent Subway System|IND]] system was similar to the IRT but reversed the terminal and line name on the destination signs: ''Queens – 179th St.'' for 179th Street terminal on the [[IND Queens Boulevard Line|Queens Boulevard Line]]. The IND also adopted a similar logical labeling system, but used them publicly on trains and maps. Single letters were used to indicate an express service and double letters indicated local service. For example, the [[CC (New York City Subway service)|CC]] ran local and the C ran express on the Concourse and Eighth Avenue Lines.

Unlike the IRT labels, the IND letter system today is significantly different from the original service pattern.
{{-}}

===Unification and post-unification===
{{unreferenced|section|date=August 2024}}
====BMT/IND service label integration====
{| class="wikitable" style="float: right; margin: 1em 0 1em 1em; width: 40%"
|+ BMT letters and old numbers, 1960 mapping
|-
! Letter
! Old number
! Line
|-
! [[J (New York City Subway service)|J]]
| style="text-align:center;"| '''15'''
| [[BMT Jamaica Line|Jamaica Line]] (express)
|-
! [[K (Broadway Brooklyn Local)|K]]
| style="text-align:center;"| '''14'''
| [[BMT Jamaica Line|Broadway–Brooklyn Line]] to Canarsie Line or Jamaica Line (local)
|-
! [[L (New York City Subway service)|L]]
| style="text-align:center;"| '''16'''
| [[BMT Canarsie Line|Canarsie Line]] via 14th Street
|-
! [[M (New York City Subway service)|M]]
| style="text-align:center;"| '''10'''
| [[BMT Myrtle Avenue Line|Myrtle Avenue Line]] from Lower Manhattan
|-
! [[M (New York City Subway service)|MJ]]
| style="text-align:center;"| '''11'''
| Myrtle Avenue Line from Downtown Brooklyn
|-
! [[N (New York City Subway service)|N]]
| style="text-align:center;"| '''4'''
| [[BMT Sea Beach Line|Sea Beach Line]]
|-
! [[Q (New York City Subway service)|Q]]
| style="text-align:center;"| '''1'''
| [[BMT Brighton Line|Brighton Beach Line]]
|-
! [[R (New York City Subway service)|R]]
| style="text-align:center;"| '''2'''
| [[BMT Fourth Avenue Line|Fourth Avenue Line]]
|-
! [[T (New York City Subway service)|T]]
| style="text-align:center;"| '''3'''
| [[BMT West End Line|West End Line]]
|-
! [[Culver Shuttle|SS]]
| style="text-align:center;"| '''5'''
| [[Culver Shuttle|Culver Line]]
|-
! [[Franklin Avenue Shuttle|SS]]
| style="text-align:center;"| '''7'''
| [[BMT Franklin Avenue Line|Brighton–Franklin Line]]
|}
When all three systems came under city ownership in 1940, essentially nothing was done to standardize signage for two decades. Stations on the IRT and BMT still said ''Interborough'' or ''BMT Lines'' or sometimes older designations. Services continued to be signed by their traditional methods for each system. IND and post-[[Second World War]] ("R-type") equipment used BMT numbers when operating on BMT services. With the introduction of [[R12 (New York City Subway car)|R12]] equipment on the IRT in 1948, IRT subway services (except for the [[42nd Street Shuttle]]) began using the route numbers still used today, which had been used internally but not on trains or maps. [[BMT Astoria Line|Astoria Line]] trains were only signed as [[8 (New York City Subway service)|8]] for a year, after which the line, which had been shared with the [[Brooklyn–Manhattan Transit Corporation|BMT]], was converted for BMT operation only (and the [[IRT Flushing Line|Flushing Line]] carried only IRT trains).

In 1960, with the delivery of the first [[R27 (New York City Subway car)|R27]] class cars for the BMT, the [[New York City Transit Authority]] (TA), which had become the operator of the combined system in 1953, began the introduction of letters for BMT services in anticipation of integrating the BMT and IND operationally. The last IND letter used was ''H'', and the letter ''I'' was skipped as being too similar to the number ''1''. The BMT Eastern Division services got the letters [[J (New York City Subway service)|J]], [[K (Broadway Brooklyn Local)|K]], [[L (New York City Subway service)|L]] and [[M (New York City Subway service)|M]], while the BMT Southern Division services were designated [[N (New York City Subway service)|N]], [[Q (New York City Subway service)|Q]], [[R (New York City Subway service)|R]] and [[T (New York City Subway service)|T]]. ''S'' was still reserved for "Special" and ''SS'' began to be used for shuttles.

Since the BMT was not amenable to the neat IND system, the TA had to make some compromises. They tried to follow the IND system of single-letter expresses and double-letter locals, but the system began to break down under the complex BMT routings. Where on the IND a local simply doubled the express letter ([[A (New York City Subway service)|A]] Eighth Avenue Express, [[AA (New York City Subway service)|AA]] Eighth Avenue Local), some lines had multiple local services with different routings. For instance the two Brighton Local services, one via the [[Manhattan Bridge]] and the other via the [[Montague Street Tunnel]], were designated [[QB (New York City Subway service)|QB]] and [[QT (New York City Subway service)|QT]] respectively. The TA had no specific lettering plan for the two Wall Street special rush-hour services, so it just designated these [[M (New York City Subway service)|M]] (Nassau Street Express) temporarily, a letter reserved for use on the [[BMT Myrtle Avenue Line]]'s Nassau Street service.

During this period, the TA did not change sign rolls on BMT equipment (the [[D-type Triplex (New York City Subway car)|D-type]]s and [[R16 (New York City Subway car)|R16]]s) that carried numbers, so that on the Brighton Line, the [[R27 (New York City Subway car)|R27]]-operated locals were signed [[QB (New York City Subway service)|QB]] or [[QT (New York City Subway service)|QT]] but the D-type-operated expresses continued to carry the number ''1''.
{{clear right}}

====Chrystie Street Connection====
{| class="wikitable"  style="float:right; clear:right;"
|-
|align=center|
{| cellpadding=4
|-
| style="text-align:center; width:12.5%; background:#f56600;"|'''[[1 (New York City Subway service)|<span style="color:white;">1</span>]]'''
| style="text-align:center; width:12.5%; background:#e60d2e;"|'''[[2 (New York City Subway service)|<span style="color:white;">2</span>]]'''
| style="text-align:center; width:12.5%; background:#00abc9;"|'''[[3 (New York City Subway service)|<span style="color:white;">3</span>]]'''
| style="text-align:center; width:12.5%; background:#e026a3;"|'''[[4 (New York City Subway service)|<span style="color:white;">4</span>]]'''
| style="text-align:center; width:12.5%; background:#332b24;"|'''[[5 (New York City Subway service)|<span style="color:white;">5</span>]]'''
| style="text-align:center; width:12.5%; background:#e6b012;"|'''[[6 (New York City Subway service)|<span style="color:white;">6</span>]]'''
| style="text-align:center; width:12.5%; background:#f56600;"|'''[[7 (New York City Subway service)|<span style="color:white;">7</span>]]'''
| style="text-align:center; width:12.5%; background:#00abc9;"|'''[[8 (New York City Subway service)|<span style="color:white;">8</span>]]'''
|-
| style="text-align:center; background:#006ec7;"|'''[[A (New York City Subway service)|<span style="color:white;">A</span>]]'''
| style="text-align:center; background:#e026a3;"|'''[[AA (Eighth Avenue Local)|<span style="color:white;">AA</span>]]'''
| style="text-align:center; background:#332b24;"|'''[[B (New York City Subway service)|<span style="color:white;">B</span>]]'''
| style="text-align:center; background:#00b052;"|'''[[CC (New York City Subway service)|<span style="color:white;">CC</span>]]'''
| style="text-align:center; background:#f56600;"|'''[[D (New York City Subway service)|<span style="color:white;">D</span>]]'''
| style="text-align:center; background:#00abc9;"|'''[[E (New York City Subway service)|<span style="color:white;">E</span>]]'''
| style="text-align:center; background:#f56600;"|'''[[EE (Queens-Broadway Local)|<span style="color:white;">EE</span>]]'''
| style="text-align:center; background:#e026a3;"|'''[[F (New York City Subway service)|<span style="color:white;">F</span>]]'''
|-
| style="text-align:center; background:#00b052;"|'''[[GG (New York City Subway service)|<span style="color:white;">GG</span>]]'''
| style="text-align:center; background:#e60d2e;"|'''[[HH (Rockaway Shuttle)|<span style="color:white;">HH</span>]]'''
| style="text-align:center; background:#332b24;"|'''[[J (New York City Subway service)|<span style="color:white;">J</span>]]'''
| style="text-align:center; background:#f56600;"|'''[[JJ (New York City Subway service)|<span style="color:white;">JJ</span>]]'''
| style="text-align:center; background:#006ec7;"|'''[[K (Broadway Brooklyn Local)|<span style="color:white;">K</span>]]'''
| style="text-align:center; background:#006ec7;"|'''[[KK (New York City Subway service)|<span style="color:white;">KK</span>]]'''
| style="text-align:center; background:#332b24;"|'''[[LL (New York City Subway service)|<span style="color:white;">LL</span>]]'''
| style="text-align:center; background:#00abc9;"|'''[[M (New York City Subway service)|<span style="color:white;">M</span>]]'''
|-
| style="text-align:center; background:#e026a3;"|'''[[MJ (New York City Subway service)|<span style="color:white;">MJ</span>]]'''
| style="text-align:center; background:#e6b012;"|'''[[N (New York City Subway service)|<span style="color:white;">N</span>]]'''
| style="text-align:center; background:#00abc9;"|'''[[NX (New York City Subway service)|<span style="color:white;">NX</span>]]'''
| style="text-align:center; background:#e60d2e;"|'''[[QB (New York City Subway service)|<span style="color:white;">QB</span>]]'''
| style="text-align:center; background:#332b24;"|'''[[QJ (New York City Subway service)|<span style="color:white;">QJ</span>]]'''
| style="text-align:center; background:#00b052;"|'''[[RR (New York City Subway service)|<span style="color:white;">RR</span>]]'''
| style="text-align:center; background:#e60d2e;"|'''[[RJ (New York City Subway service)|<span style="color:white;">RJ</span>]]'''
| style="text-align:center; background:#006ec7;"|'''[[TT (New York City Subway service)|<span style="color:white;">TT</span>]]'''
|-
| style="text-align:center; background:#332b24;"|'''[[SS (New York City Subway service)|<span style="color:white;">SS</span>]]'''
|colspan=3|145&nbsp;Street<br/>135&nbsp;Street
| style="text-align:center; background:#00b052;"|'''[[SS (New York City Subway service)|<span style="color:white;">SS</span>]]'''
|colspan=3|Dyre&nbsp;Avenue<br/>East&nbsp;180&nbsp;Street
|-
| style="text-align:center; background:#006ec7;"|'''<span style="color:white;">[[Bowling Green–South Ferry shuttle|<span style="color:white;">SS</span>]]</span>'''
|colspan=3|Bowling&nbsp;Green<br/>South&nbsp;Ferry
| style="text-align:center; background:#00abc9;"|'''[[42nd Street Shuttle|<span style="color:white;">SS</span>]]'''
|colspan=3|Grand&nbsp;Central<br/>Times&nbsp;Square
|-
| style="text-align:center; background:#e6b012;"|'''[[Franklin Avenue Shuttle|<span style="color:white;">SS</span>]]'''
|colspan=3|Prospect&nbsp;Park<br/>Franklin&nbsp;Avenue
| style="text-align:center; background:#f56600;"|'''[[SS (New York City Subway service)|<span style="color:white;">SS</span>]]'''
|colspan=3|9&nbsp;Avenue<br>Ditmas&nbsp;Avenue
|}
|-
|align=center|Former service colors, 1967–1979<br>(shuttles all became green in 1968)
|}
[[File:Sample post Chrystie rollsign.svg|thumb|left|200px|A typical post-1967 side [[rollsign]]]]
In anticipation of the 1967 opening of the [[Chrystie Street Connection]], which combined two major BMT and IND services as single routes and resulted in numerous other changes (especially on the ''[[BMT 14|14]]'' and ''[[BMT 15|15]]''), the TA decided to adopt universal systems of signage and nomenclature. The rationale was that this would make the system more consistent and more understandable for newcomers to the city and [[tourist]]s, who were presumed to be uninterested in or even confused by historic or community names, or might not be native English speakers.
* Branch line names would be eliminated from signage and maps; all services that had Manhattan mainlines would be identified by those names only.
* Services would be identified only by letters or numbers wherever possible, even when announcing reroutings.
* Terminals would be identified by street names rather than community names where that existed. This had actually begun with the introduction of R-type equipment, when destinations such as ''Woodlawn'' and ''Canarsie'' were changed to read ''Woodlawn Road'' (which is no longer the name of a road) and ''Rockaway Parkway''.
* All services would be color-coded for map and [[rollsign]] purposes. This proved a daunting task, since the TA wanted to ensure that no two services with exactly the same color would operate over the same line. With a lot of imagination and a lot of color variations, this goal was achieved but proved unwieldy. The colors did not have any particular logic and still produced ambiguity; notably the [[A (New York City Subway service)|A]] service and the [[E (New York City Subway service)|E]] service shared miles of line between [[Midtown Manhattan]] and the [[IND Rockaway Line|Rockaway Line]] in Queens, one as an express, the other as a local. But the A was colored dark blue and the E light blue, not always easily distinguishable.

The [[8 (New York City Subway service)|8]] designation was brought back for the only remaining [[Interborough Rapid Transit Company|IRT]] [[elevated railway|elevated]] service, the [[IRT Third Avenue Line]] in [[the Bronx]] but trains never displayed the number. When the Lo-V cars (which did not have front signs) were replaced by [[R12 (New York City Subway car)|R12]] cars the front roll signs in use did not contain the number 8 and instead displayed the word ''shuttle''. For map and sign purposes [[MJ (New York City Subway service)|MJ]] was assigned to the last old-style elevated line, standing for "Myrtle Avenue Line to Jay Street", while the "Myrtle Avenue Line to Chambers Street" subway service would finally receive its [[M (New York City Subway service)|M]] designation. The short-lived new [[BMT Sea Beach Line|Sea Beach Line]] super-express service was made [[NX (New York City Subway service)|NX]]. The [[Q (New York City Subway service)|Q]], [[QT (New York City Subway service)|QT]] and [[T (New York City Subway service)|T]] disappeared when the Chrystie Street Connection opened; thus they never had colors (until after the elimination of double letters, when the [[Q (New York City Subway service)|Q]] came back; by that time the current color system was in place). By 1968, all shuttles (''SS'') were green. For a short time, the off-hour shuttle between Metropolitan Avenue and Myrtle Avenue was added in 1969 when the [[MJ (New York City Subway service)|MJ]] service to Jay Street was discontinued, and that part of the line abandoned. The shuttle was soon renamed "M", however, as it only ran when the M did not run to Manhattan.

The system immediately showed evidence of problems for various reasons:
* Different services at common stations shared common destinations by different routes. [[N (New York City Subway service)|N]], [[B (New York City Subway service)|B]] and [[QJ (New York City Subway service)|QJ]] services arriving at [[DeKalb Avenue (BMT Broadway Line)|DeKalb Avenue]], for example, all had [[Coney Island]] as a destination, but had no mention of the widely separated routes ([[BMT Sea Beach Line|Sea Beach Line]], [[BMT West End Line|West End Line]], [[BMT Brighton Line|Brighton Line]]) used to get there.
* Service labels are ephemeral. The TA has frequently shifted lettered routes from one branch line to another, and introduced, changed or deleted letters, making a description like "the D train" meaningless. The [[D (New York City Subway service)|D]] service has been on three completely different [[Brooklyn]] branch lines since 1954. [[K (Broadway Brooklyn Local)|K]] was introduced for a service on the [[BMT Jamaica Line|Broadway-Brooklyn Line]] but was later used for the [[IND Eighth Avenue Line]] local which had formerly been [[AA (New York City Subway service)|AA]].
* The same lettered or numbered lines may have different destinations by time of day, despite a largely successful effort to minimize this problem.

====Elimination of double letters====
[[File:Hey, What's a "K" train? brochure 2.gif|left|thumb|This brochure was published in 1985 to explain the relabeling of double-letter subway services]]
On June 25, 1979, the former color scheme was scrapped, and the TA settled on the more coherent policy of assigning the same color to every service on each Manhattan mainline, as well as the color lime green for the [[IND Crosstown Line]], which does not enter Manhattan. The same colors are still used today. Nevertheless, no New York subway line is officially referred to by its color, e.g., BMT Broadway Line services as the "Yellow Line."  While referring to lines by their color, as is common in some other cities, is a convenient shorthand for the regions of Manhattan where lines and colors are relatively unambiguous (from roughly Houston Street to 50th Street, and further uptown for the "red" and "green" lines), this practice would be confusing outside of that region (due to multiple services being assigned the same color).

{| class="wikitable"  style="width:25%; float:right; clear:right;"
|-
|align=center|
{| cellpadding="4" style="width:100%;"
|-
| style="text-align:center; background:#0079c3;"|'''[[AA (New York City Subway service)|<span style="color:white;">AA</span>]]'''
|→
| style="text-align:center; background:#0079c3;"|'''[[K (Eighth Avenue Local)|<span style="color:white;">K</span>]]'''
|8th Avenue Local
|-
| style="text-align:center; background:#0079c3;"|'''[[CC (New York City Subway service)|<span style="color:white;">CC</span>]]'''
|→
| style="text-align:center; background:#0079c3;"|'''[[C (New York City Subway service)|<span style="color:white;">C</span>]]'''
|8th Avenue Local (rush hour "diamond" service)
|-
| style="text-align:center; background:#0079c3;"|'''[[CC (New York City Subway service)|<span style="color:white;">CC</span>]]'''<span style="color:white;">/</span>'''[[A (New York City Subway service)|<span style="color:white;">A</span>]]'''
|→
| style="text-align:center; background:#0079c3;"|'''[[H (New York City Subway service)|<span style="color:white;">H</span>]]'''
|Rockaway Shuttle
|-
| style="text-align:center; background:#afd335;"|'''[[GG (New York City Subway service)|<span style="color:white;">GG</span>]]'''
|→
| style="text-align:center; background:#afd335;"|'''[[G (New York City Subway service)|<span style="color:white;">G</span>]]'''
|Brooklyn-Queens Crosstown
|-
| style="text-align:center; background:#b0b4b6;"|'''[[LL (New York City Subway service)|<span style="color:white;">LL</span>]]'''
|→
| style="text-align:center; background:#b0b4b6;"|'''[[L (New York City Subway service)|<span style="color:white;">L</span>]]'''
|14th Street-Canarsie Local
|-
| style="text-align:center; background:#fddd15;"|'''[[QB (New York City Subway service)|<span style="color:black;">QB</span>]]'''
|→
| style="text-align:center; background:#fddd15;"|'''[[Q (New York City Subway service)|<span style="color:black;">Q</span>]]'''
|Broadway Express (had been rush hour "diamond" service)
|-
| style="text-align:center; background:#fddd15;"|'''[[RR (New York City Subway service)|<span style="color:black;">RR</span>]]'''
|→
| style="text-align:center; background:#fddd15;"|'''[[R (New York City Subway service)|<span style="color:black;">R</span>]]'''
|Broadway Local
|-
| style="text-align:center; background:#fddd15;"|'''[[RR (New York City Subway service)|<span style="color:black;">RR</span>]]'''
|→
| style="text-align:center; background:#fddd15;"|'''[[R (New York City Subway service)|<span style="color:black;">R</span>]]'''
|Nassau Street Local (rush hour "diamond" service; shown as both a yellow diamond<ref name=ktrain/> and a brown diamond<ref>New York City Subway Map, edition of May 24, 1987, code# 2 3 4 5 6 7 8; see also [http://www.nycsubway.org/perl/caption.pl?/img/maps/system_1987.gif hand drawn facsimile]</ref>)
|}
|-
|align=center|1985 letter changes<ref name=ktrain>[http://thejoekorner.com/brochures/index-whats-the-k.html Hey, What's a "K" Train?] MTA service notice, 1985</ref>
|}

On May 5, 1985, the last significant change in route identification policy was made after the TA had decided in 1981 that the single and double letter system of the original IND was no longer meaningful, given that there were many services that were express for part of their route and local for other parts. In most cases, this was accomplished by simply eliminating the second letter in route designations. There is no longer a letter designation for specials (formerly ''S'').

By the 1990s, the TA were moving steadily toward using traditional line names on maps and especially on signage. All of the southern Brooklyn subway lines now show the traditional line names (except for the [[BMT Fourth Avenue Line]]) in order to distinguish between services going to [[Coney Island–Stillwell Avenue (New York City Subway)|Coney Island]] via different lines. On BMT/IND equipment, branch line names frequently appear on operating trains, in addition to the route letter. [[R32 (New York City Subway car)|R32]] equipment with [[rollsign]]s, for example, may read:

{{clear left}}
{{col-begin|width=60%}}
{{col-break}}
{| border=0 cellspacing=0
|style="border:solid 1px gray;"|[[Inwood–207th Street (IND Eighth Avenue Line)|207 Street]]<br>[[Manhattan]]
|-
|style="border-left:solid 1px gray;border-right:solid 1px gray;"| [[Far Rockaway–Mott Avenue (IND Rockaway Line)|Mott Av]]<br>[[Far Rockaway, Queens|Far Rockaway]]
|-
|style="border:solid 1px gray;"|{{rint|newyork|A}}<small>  [[Washington Heights, Manhattan|Wash Hts]]/[[IND Eighth Avenue Line|8 Av]]/[[IND Fulton Street Line|Fulton]]</small>
|}
{{col-break}}
{| border=0 cellspacing=0
|style="border:solid 1px gray;"|[[Astoria–Ditmars Boulevard (BMT Astoria Line)|Ditmars Blvd]]<br>[[Astoria, Queens|Astoria]]
|-
|style="border-left:solid 1px gray;border-right:solid 1px gray;"|[[Coney Island–Stillwell Avenue (New York City Subway)|Stillwell Av]]<br>[[Coney Island]]
|-
|style="border:solid 1px gray;"|{{rint|newyork|N}} <small>[[Astoria, Queens|Astoria]]/[[BMT Broadway Line|Bway]]/[[BMT Sea Beach Line|Sea Beach]]</small>
|}
{{col-break}}
{| border=0 cellspacing=0
|style="border:solid 1px gray;"|[[57th Street–Seventh Avenue (BMT Broadway Line)|57 St–7 Av]]<br>[[Manhattan]]
|-
|style="border-left:solid 1px gray;border-right:solid 1px gray;"|[[Coney Island–Stillwell Avenue (New York City Subway)|Stillwell Av]]<br>[[Coney Island]]
|-
|style="border:solid 1px gray;"|{{rint|newyork|Q}} <small> [[BMT Broadway Line|Broadway]]/[[BMT Brighton Line|Brighton]]</small>
|}
{{col-end}}
{{-}}
Newer rollsigns on [[R40/A (New York City Subway car)|R40]] up to the [[R68A (New York City Subway car)|R68A]] (including the former rollsigns on the [[R44 (New York City Subway car)|R44]] and [[R46 (New York City Subway car)|R46]] that now have LCD displays) have the route's bullet on the left side, and the two destinations on the right side. A rollsign on an [[R68 (New York City Subway car)|R68]] ''{{NYCS|D}}'' train may read:

{| border=0 cellspacing=0
|style="border:solid 1px gray;" rowspan=2|{{rint|newyork|D|size=80}}
|style="border-top:solid 1px gray;border-right:solid 1px gray;" align=center|<small>[[Norwood, Bronx]]<br>[[Norwood – 205th Street (IND Concourse Line)|205 St]]</small>
|-
|style="border-top:solid 1px gray;border-bottom:solid 1px gray;border-right:solid 1px gray;" align=center|[[Coney Island – Stillwell Avenue (New York City Subway)|Coney Island]]
|}

One change which precedes pre-unification has to do with the use of locality names. While these were discouraged during the 1960s after they had been inherited from private operators, many terminal stations are once again described by both a community and a street name, e.g., [[Inwood–207th Street (IND Eighth Avenue Line)|''Inwood''–207th Street]] for the northern destination of the ''[[A (New York City Subway service)|A]]'' service, and [[Wakefield–241st Street (IRT White Plains Road Line)|''Wakefield''–241st Street]] for the northern destination of the ''[[2 (New York City Subway service)|2]]'' service.

[[File:R142 Sign.jpg|200px|left|thumb|An [[R142 (New York City Subway car)|R142]] side sign indicating that this 4 train runs express on the IRT Eastern Parkway Line]]
[[File:NYCS 4 destination sign.gif|200px|left|thumb|The same sign shown in animation]]

The [[JFK Express]], started in 1978 and discontinued in 1990, used a turquoise bullet with an airplane symbol; this stayed through the color change. The color will be reused in the distant future when the [[Second Avenue Subway]] is complete.

====Route consistency====
Since the unsuccessful attempts at applying the briefly popular [[schematic]] theory of diagrammatic maps, line-by-line color-coding, and exclusive use of numbers and letters for service and line descriptions, the MTA has moved steadily toward a more traditional approach, with more geographically correct maps and use of traditional line and community names on maps and public signage. Concurrently, it has been refining its use of the number and letter system to try to achieve consistency across the system.

One major push has been an attempt to have as many services as possible serve the same stations, routes and terminals at all times, with the major exception for most services being the early morning hours of approximately midnight to 5&nbsp;a.m. For instance, the [[B (New York City Subway service)|B]] and [[C (New York City Subway service)|C]] swapped northern terminals in 1998 so the C could serve the entire local portion of the [[IND Eighth Avenue Line]] at all times except nights; previously, the [[A (New York City Subway service)|A]] had made two local stops north of [[145th Street (IND Eighth Avenue Line)|145th Street]] on weekends, while being express on the whole line south of 145th Street, because the B did not operate in Manhattan on weekends. In another case, the MTA took advantage of unavoidable service changes forced by the partial [[Manhattan Bridge]] closures to swap the Brooklyn segments of the B and [[D (New York City Subway service)|D]] services, with the B becoming the [[BMT Brighton Line]] express service and the D becoming the [[BMT West End Line]] local (previously the B had been the West End Local and the D the Brighton Local). This enabled the D, a full-time service, to operate continuously on the same route and terminals from [[Norwood–205th Street (IND Concourse Line)|Norwood–205th Street]] in [[the Bronx]] to [[Coney Island–Stillwell Avenue (BMT West End Line)|Coney Island–Stillwell Avenue]] in [[Brooklyn]], while the part-time B became the part-time Brighton Express service, formerly served by the express [[Q (New York City Subway service)|&lt;Q&gt;]] (notated with a diamond).

==Table of service label and color use==
{{See also|List of New York City Subway services#History}}
This is a table of when each service has existed (and been signed for the public). Shuttles were [[SS (New York City Subway service)|SS]] until 1985, when they became [[S (New York City Subway service)|S]] (which had been used for specials). Colors reflected in the table correspond to the official MTA issued maps; rollsign colors are not always consistent with that.

Various colors were used for shuttles in 1967; in 1968 all six became green, and in 1979 all shuttles became dark gray.

{{NYCS const|list|services|timeline}}

== References ==
{{reflist}}

== Further reading ==
* The Best Subway Map in Years, [[New York Times]] July 1, 1979 page E20

== External links ==
* [http://www.nycsubway.org/wiki/Historical_Maps NYCsubway.org – Historical Maps]
* [http://nycsubway.org/recent/ NYCsubway.org – Post-War to Today]
* [http://nycsubway.org/faq/subway-markers.html NYCsubway.org – FAQ: The Letter, Number and Color Codes of the New York Subways]
* [https://web.archive.org/web/20011202055509/http://members.aol.com/bdmnqr2/linehistory.html Line by Line History]

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[[Category:New York City Subway lines|*]]
[[Category:New York City Subway services|*]]
[[Category:New York City Subway stations|*]]
[[Category:History of the New York City Subway|*]]
[[Category:New York City Subway]]