Independent Subway System

Independent Subway System (IND)
Company type	Municipal rapid transit network
Industry	Public transportation
Founded	1932
Fate	Incorporated into New York City Subway in 1940
Headquarters	New York City, United States
Area served	New York City
Products	Rapid transit services

The Independent Subway System (IND; previously known as ISS) was a rapid transit network in New York City that has since been incorporated into the New York City Subway. Its inaugural route, the Eighth Avenue Line, commenced operations in Manhattan in 1932. Sometimes referred to as the Independent City-Owned Subway System (ICOSS) or the Independent City-Owned Rapid Transit Railroad (ICORTR), this system was municipally owned and managed, setting it apart from the privately controlled Interborough Rapid Transit Company (IRT) and Brooklyn–Manhattan Transit Corporation (BMT). The IND combined with these other networks during the subway unification process in 1940.

The original IND routes correspond to what are now the A, C, E, F, and G lines, along with segments of the B and D lines outside Brooklyn. Furthermore, BMT's M and R services operate on former IND tracks, while the Q runs along the post-unification IND Second Avenue Line. The Rockaway Park Shuttle serves as a supplementary route to the A line. From an operational standpoint, both IND and BMT lines are categorized under the B Division.

Nomenclature

Prior to 1940, this system was identified as the Independent City-Owned Subway System (ICOS), Independent Subway System (ISS), or Independent City-Owned Rapid Transit Railroad. Following the subway consolidation in 1940, it adopted the name IND, which matched the three-letter acronyms used by IRT and BMT.

The initial IND route, the Eighth Avenue Line in Manhattan, opened on September 10, 1932, and was initially known as the Eighth Avenue Subway. Most of the original IND network runs underground throughout its four boroughs, with the exception of a brief stretch of the IND Culver Line crossing over the Gowanus Canal in Brooklyn.

History

In the early 1920s, Mayor John Hylan advocated for city-owned rapid transit lines to compete against BMT and IRT, focusing particularly on elevated lines. Established in 1921, the New York City Transit Commission sought to alleviate subway congestion through plans that included:

Two primary trunk lines in Midtown Manhattan—one beneath Eighth Avenue and another under Sixth Avenue, which already had an elevated line
A crosstown subway along 53rd Street connecting to Queens Plaza via a Brooklyn–Queens crosstown line, extending beneath Queens Boulevard and Hillside Avenue toward Jamaica – 179th Street, incorporating bus connections
A subway line running under the Grand Concourse in the Bronx, branching off from the Eighth Avenue Line at 145th Street and Saint Nicholas Avenue

These routes were largely built according to these designs. Apart from a short section of the Culver Line spanning the Gowanus Canal, all are located underground.

Construction for the Eighth Avenue subway began on March 14, 1925, at the intersection of 123rd Street and St. Nicholas Avenue.

On July 8, 1931, the first R1 subway cars traveled from Coney Island via the BMT Sea Beach Line to Times Square, completing the journey in 42 minutes.

Initial Manhattan Trunk Line, 1932

The IND system commenced operations on September 10, 1932, with the opening of the IND Eighth Avenue Line stretching from 207th Street down to Chambers Street. By February 1933, service extended through the Cranberry Street Tunnel connecting Chambers Street to Jay Street–Borough Hall. The Bronx segment via the IND Concourse Line was inaugurated on July 1, 1933, running between 205th Street and 145th Street.

At the system's debut, the IND operated a total of 300 subway cars, in contrast to the IRT’s fleet comprising 2,281 subway cars plus 1,694 elevated cars and the BMT’s count of 2,472 cars.

The construction of the Eighth Avenue Line utilized substantial materials including extensive amounts of concrete and steel, with infrastructure designed for a projected service life of approximately three decades. Simultaneously, five underwater tunnels were constructed to facilitate expanded transit access across boroughs:

Early operational issues involved vandalism at stations uptown and incidents of theft that necessitated closing several station exits at 96th Street and 103rd Street just two months after opening.

Initial Branch Lines

The Queens Boulevard Line—previously referred to before its launch as the Long Island City−Jamaica Line, Fifty-third Street−Jamaica Line, and Queens Boulevard−Jamaica Line—was a pivotal segment of the city-owned IND system aimed at linking Manhattan’s Eighth Avenue corridor with Jamaica in Queens.

The first portion from Roosevelt Avenue to 50th Street began service on August 19, 1933. This extension facilitated economic activity by allowing E trains to operate local routes terminating at Manhattan’s Hudson Terminal (currently the World Trade Center), while the precursor to today’s G train functioned as a shuttle between Queens Plaza and Nassau Avenue.

The Cranberry Street Tunnel, which carries express tracks beneath Fulton Street to Jay Street–Borough Hall in Brooklyn, opened on February 1, 1933, improving interborough transit connections. Initially, the High Street station was not served until June 24, 1933.

The first segment of the IND Culver Line became operational on March 20, 1933, extending express services southward from Jay Street to Bergen Street, with full completion reaching Church Avenue by October 7, 1933. This development brought subway lines closer to existing elevated routes, enhancing transit network integration. In 1936, service patterns changed with the A train redirected to the IND Fulton Street Line, replaced by trains originating from Queens Boulevard.

Second Manhattan trunk line, 1936–1940

The first portion of the IND Sixth Avenue Line, originally named the Houston–Essex Street Line, commenced operations on January 1, 1936. This segment included two local tracks extending from a junction with the Eighth Avenue Line located south of West Fourth Street–Washington Square, running eastward beneath Houston Street and then southward under Essex Street, terminating temporarily at East Broadway. The E trains, which operated between Jackson Heights, Queens and Hudson Terminal, were redirected to utilize this newly established route. Additionally, two express tracks were constructed beneath Houston Street toward Essex Street-Avenue A, designed to eventually connect via the East River to the planned but never realized IND Worth Street Line in Brooklyn.

Service under the East River began on April 9, 1936, through the Rutgers Street Tunnel, linking the Houston-Essex Street Line with the northern end of the IND Culver Line at Jay Street–Borough Hall. At this point, E trains extended their route to Church Avenue. Simultaneously, the IND Fulton Street Line reached Rockaway Avenue, prompting rerouting of A and C trains from Smith Street to this new extension.

During this period of development, streetcar operations along Sixth Avenue were discontinued. To facilitate quicker dismantling of the IRT Sixth Avenue Line and reduce expenses, the city acquired it for $12.5 million and ceased its service on December 5, 1938.

On December 15, 1940, local subway service was inaugurated along Sixth Avenue from West Fourth Street to 47-50th Street, providing a connection to the IND 53rd Street Line. The construction of this segment cost $59.5 million. The following services were introduced:

AA Washington Heights Local operating during off-peak hours between 168th Street and Hudson Terminal via Eighth Avenue.
BB Washington Heights Local serving rush hour commuters between 168th Street and Hudson Terminal via Sixth Avenue.
D Bronx Concourse Express running from Norwood–205th Street to Hudson Terminal along Sixth Avenue.
E Queens–Manhattan Express shortened from Church Avenue to Broadway–Lafayette.
F Queens–Manhattan Express added service between Parsons Boulevard and Church Avenue via Sixth Avenue.

Express operations on Sixth Avenue began in 1967 following the inauguration of the Chrystie Street Connection.

Additional branch lines inaugurated

The IND Fulton Street Line was extended from Jay Street to Rockaway Avenue on April 9, 1936. This included a stub terminal at Court Street, where a shuttle service ran between Court Street and Hoyt–Schermerhorn Streets.

On December 31, 1936, the Queens Boulevard Line was extended from Roosevelt Avenue to Kew Gardens–Union Turnpike. Further expansion took place on April 24, 1937, reaching Hillside Avenue and 178th Street with a terminal established at 169th Street. On that same day, express service started during peak hours on the Queens Boulevard Line: E trains operated express west of 71st–Continental Avenues while GG trains assumed local duties. Initial express intervals ranged from three to five minutes.

Completion of the entire Crosstown Line occurred on July 1, 1937, when it connected with the IND Culver Line, extending the GG service in both directions to Smith–Ninth Streets and Forest Hills–71st Avenue.

Between April 30, 1939, and October 28, 1940, the Queens Boulevard Line provided service to the 1939 New York World's Fair through the World's Fair Railroad, which passed through the Jamaica Yard and Flushing Meadows–Corona Park along what is currently known as the Van Wyck Expressway. Despite efforts by officials such as Queens Borough President George Harvey to preserve this link to northern Queens, the line was dismantled in 1941.

Planned Extensions

In 1922, Mayor John Hylan introduced a series of subway expansion plans that were never realized, envisioning growth even before the initial IND segment was operational. Significant elements of his proposals included:

A West Side main line running through Manhattan from 14th Street up to Yonkers, incorporating multiple track segments and linking to the BMT Canarsie Line as well as Brooklyn via a tunnel beneath the East River.
A four-track First Avenue main line stretching from the Harlem River down to 10th Street, which would branch off to serve both Brooklyn and City Hall, connecting with existing IRT routes.
A crosstown route at 125th Street designed to connect Manhattan with Astoria in Queens.
A new subway line extending southeast from Hunters Point Avenue in Queens to Lafayette Avenue in Brooklyn, with additional branches reaching Flatbush and Franklin Avenues.
A four-track corridor originating at Brooklyn’s Borough Hall, proceeding along Lafayette Avenue to Cypress Hills, running parallel to the BMT Jamaica Line and competing for ridership.
Branch lines diverging from current routes including Utica Avenue and Flatbush Avenue toward Coney Island, plus extensions of both the BMT Canarsie and Fourth Avenue Lines.
Proposed links connecting Staten Island via the Staten Island Tunnel along with further expansions in Queens on Flushing and Main Streets.

A comprehensive IND expansion plan was unveiled in 1929, targeting over 100 miles of new subway lines across Manhattan, Brooklyn, Queens, and the Bronx. This ambitious initiative sought to ensure that residents in these boroughs would live within half a mile of subway service. The projected cost was approximately US$438 million, excluding property acquisition and equipment expenses—surpassing the initial phase’s US$338 million total. However, the onset of the 1929 Wall Street Crash and the subsequent Great Depression forced these plans to be shelved.

Efforts to revive expansion proposals occurred intermittently during 1939, 1940, 1951, as part of the 1968 Program for Action, and again in 1998, though none came to fruition. During this timeframe, considerations were also made for extensive elevated line development within the IND system.

The Second Avenue Subway—one component of these long-term ambitions—finally saw its inaugural phase open between 63rd and 96th Streets on January 1, 2017.

Post-unification Developments

Due to low passenger usage, the Court Street station on the IND Fulton Street Line ceased operations on June 1, 1946. Following World War II, availability of materials and labor facilitated extending service to the more effective Broadway Junction terminal, which began service on December 30, 1946. The Fulton Street Line extension—delayed by wartime constraints and financed under Mayor William O'Dwyer—was completed on November 28, 1948. This expansion extended service along Pennsylvania and Pitkin Avenues reaching Euclid Avenue near Queens at a cost near $46.5 million. Included was the construction of Pitkin Yard with capacity for storing 585 subway cars across 40 tracks. To accommodate this growth, forty additional R10 cars were introduced.

The then-terminal station at 169th Street was insufficient for handling a four-track line; therefore, construction commenced in 1946 to extend the Queens Boulevard Line further eastward to 179th Street. This extension featured improved facilities for express and local services as well as train storage capabilities. Despite setbacks caused by the Great Depression and World War II, this segment opened on December 11, 1950, enabling both E and F trains to run further east.

During the 1950s, the IND system expanded by absorbing elevated lines formerly operated by the BMT: specifically, the Culver Line in 1954 and an extension of the Fulton Street Line along Liberty Avenue in 1956. The Culver Ramp created a connection between IND and BMT Culver Lines near Ditmas Avenue allowing IND trains access to Coney Island. The Liberty Avenue Elevated linked Euclid Avenue with Lefferts Boulevard via Grant Avenue station.

Service on the IND Rockaway Line between Euclid Avenue and Rockaway Park/Wavecrest commenced on June 28, 1956. The Far Rockaway–Mott Avenue station opened subsequently on January 16, 1958 completing this route.

The initial phase of the Chrystie Street Connection launched in November 1967 introducing new express tracks on the Sixth Avenue Line alongside a Manhattan Bridge connection. This resulted in several service adjustments: BB trains were rebranded as B trains with extensions via express tracks into Brooklyn; D trains were rerouted through Brighton Line; F trains extended service to Coney Island during peak hours.

In July 1968, the opening of the 57th Street station coincided with a new link to the Williamsburg Bridge. The KK line began operating from 57th Street to 168th Street along the BMT Jamaica Line. During off-peak hours B trains ran local on Sixth Avenue while D trains maintained express service throughout all times.

December 1988 marked the inauguration of the IND Archer Avenue Line running from Jamaica Center–Parsons/Archer to Jamaica–Van Wyck.

After nearly twenty years of construction investment totaling $898 million, the IND 63rd Street Line debuted on October 29, 1989. It extended service from 57th Street with stations at Lexington Avenue, Roosevelt Island, and Queens’ 21st Street-41st Avenue. Initially served by Q (weekdays), B (weekends), F (nights), and JFK Express trains, it lacked a direct connection to Queens Boulevard Line.

Planning for that crucial connector began in December 1990; construction started September 1994 with a final expenditure of $645 million. This connector opened for rerouting trains in December 2000 and entered full operation by December 2001 when F trains shifted routing through the 63rd Street Tunnel. This reconfiguration freed capacity on the older 53rd Street Tunnel allowing introduction of a new local Queens Boulevard service (V train), later replaced by an M train extension in 2010.

These strategic expansions represent deliberate investments aimed at enhancing New York City’s subway infrastructure by boosting operational efficiency, broadening reach within boroughs, increasing transit capacity—all pivotal factors driving ridership growth and modernizing system performance.

The Bronx and Manhattan

Concourse Line (): runs beneath the Grand Concourse from 205th Street down to 161st Street, then turns westward under the Harlem River entering Manhattan, continuing south to join the Eighth Avenue Line, closely following the path of the IRT Jerome Avenue Line.
Eighth Avenue Line (): stretches from 207th Street heading south beneath Broadway, Saint Nicholas Avenue, Eighth Avenue, Greenwich Avenue, Sixth Avenue (with a junction at Houston Street), Church Street, and Fulton Street; it crosses the East River through the Cranberry Street Tunnel into Brooklyn to connect with the Fulton Street Line, running roughly parallel to the IRT Ninth Avenue Line.
Sixth Avenue Line (): diverges from the Eighth Avenue Line at 53rd Street, extends two blocks east to Sixth Avenue, then proceeds south under Sixth Avenue to a junction north of Houston Street; it continues east beneath Houston Street and then south under Essex and Rutgers Streets to the Rutgers Street Tunnel leading into Brooklyn—mirroring the route of the IRT Sixth Avenue Elevated.
Queens Boulevard Line (): enters Manhattan via the 53rd Street Tunnel from Queens, travels west beneath 53rd Street past a junction with the Sixth Avenue Line, merging into the Eighth Avenue Line—partially paralleling the IRT Sixth Avenue Elevated connection to the IRT Ninth Avenue Elevated along 53rd Street.

East River tunnels

53rd Street Tunnel () – facilitates Queens Boulevard Line service
Rutgers Street Tunnel () – connects Sixth Avenue Line with Culver Line
Cranberry Street Tunnel () – links Eighth Avenue Line to Fulton Street Line

Brooklyn and Queens

Queens Boulevard Line (): extends from 169th Street westward beneath Hillside Avenue, Queens Boulevard, Broadway, Northern Boulevard, and 44th Drive culminating at the 53rd Street Tunnel into Manhattan.
Crosstown Line (): branches off from Queens Boulevard Line at Queens Plaza, runs south underneath Jackson, Manhattan, Union, Marcy, and Lafayette Avenues; intersects with Fulton Street Line and connects further south into Culver Line.
Culver Line (initially known as Smith Street Line) (): runs from Rutgers Street Tunnel southward under Jay and Smith Streets, surfaces briefly over Gowanus Canal near Ninth Street before submerging again along Ninth Street, Prospect Park West, Prospect Avenue, Fort Hamilton Parkway, and McDonald Avenue reaching Church Avenue; subsequently extended along BMT Culver Line.
Fulton Street Line (): operates from Court Street (currently New York Transit Museum) and Cranberry Street Tunnel eastward under Fulton Street to Rockaway Avenue; later expanded east along BMT Liberty Avenue Elevated, paralleling BMT Fulton Street Elevated.

Post-1940 expansions

After 1940, significant extensions and interconnections broadened the IND system's coverage and integration with other lines:

Queens Boulevard Line: lengthened eastward to 179th Street
Culver Line: extended southward following former BMT Culver Line tracks
60th Street Tunnel Connection: established a link between BMT's 60th Street Tunnel and Queens Boulevard Line
Fulton Street Line: pushed further east over BMT's Liberty Avenue Elevated
Rockaway Line: extended south from Fulton Street Line beyond Rockaway Boulevard
Chrystie Street Connection: connected Houston Street (Sixth Avenue) line to BMT lines crossing both the Williamsburg Bridge and Manhattan Bridge
Archer Avenue Line: extended from Queens Boulevard at Van Wyck Boulevard southeastward to Jamaica Center
63rd Street Line: linked Sixth Avenue and Queens Boulevard Lines through the 63rd Street Tunnel with connection to BMT 63rd Street line

Extension partially in service:

IND Second Avenue Line: operates between 96th Street and 72nd Street, connecting with BMT 63rd Street line

Line planning

Numerous IND routes were deliberately aligned alongside preexisting IRT and BMT lines to capture ridership and supplant outdated infrastructure:

The IND Concourse Line runs parallel to the IRT Jerome Avenue Line and was also intended to replace the NYW&B-owned IRT Dyre Avenue Line along with the IRT White Plains Road Line.
The IND Eighth Avenue Line lies within a quarter-mile of the IRT Broadway–Seventh Avenue Line and IRT Lenox Avenue Line, designed as a successor to the IRT Ninth Avenue Line.
The IND Sixth Avenue Line was developed to take the place of the former IRT Sixth Avenue Line.
The IND Fulton Street Line parallels both the IRT Eastern Parkway Line and the IRT New Lots Line, aiming to replace the BMT Fulton Street elevated line.
The IND Crosstown Line was created to substitute BMT streetcar services.
The proposed Second Avenue Subway was planned to run alongside the IRT Lexington Avenue Line, intended as a replacement for the IRT Second and Third Avenue Lines.

Additional proposed but unconstructed lines sought to replace elevated routes:

IND Second Avenue was designed to reclaim service over the IRT Dyre Avenue and Pelham Lines.
IND Utica Avenue and Archer Avenue Lines were planned to supplant portions of the BMT Jamaica Line; Archer Avenue also aimed at substituting the Long Island Rail Road's Atlantic Branch.

Service letters

The initial IND train identification system utilized three main criteria: the Manhattan trunk line served (either 8th or 6th Avenue), the northern branch line destination (Washington Heights, Grand Concourse/Bronx, or Queens Boulevard), and whether the train operated express or local service. Routes on 8th Avenue were designated A, C, and E; those on 6th Avenue were B, D, and F. Single-letter symbols indicated express trains, while double letters denoted local services. The letter G identified Brooklyn-Queens "Crosstown" service, and H was assigned to Fulton Street line trains that did not originate in Manhattan.

Original designations included:

A/AA for 8th Avenue–Washington Heights service
BB for 6th Avenue–Washington Heights local trains
C/CC for 8th Avenue–Concourse routes
D for 6th Avenue–Concourse express service
E for 8th Avenue–Queens Boulevard express
F for 6th Avenue–Queens Boulevard express
G/GG for Brooklyn-Queens Crosstown operations
HH for Fulton Street line

Most of these codes were utilized during regular or special operations at some point; for instance, "G" served the World's Fair Station in 1939.

Before the opening of the Chrystie Street Connection, service designations included:

	Line	Routing	Notes
A	Washington Heights Express	207th Street – Lefferts Boulevard/Far Rockaway/Rockaway Park (via Eighth Avenue)	currently active
AA	Washington Heights Local	168th Street – Hudson Terminal (via Eighth Avenue)	renamed K; service discontinued
BB	Washington Heights Local	168th Street – 34th Street (via Sixth Avenue)	renamed B; now runs Bedford Park Boulevard to Brighton Beach
C	Bronx Concourse Express	205th Street – Utica Avenue (via Eighth Avenue)	discontinued; merged into A and D lines
CC	Bronx Concourse Local	Bedford Park Boulevard – Hudson Terminal (via Eighth Avenue)	became C; current route from 168th Street to Euclid Avenue
D	Bronx Concourse Express	205th Street – Coney Island (via Sixth Avenue and Culver Line)	active; trains currently use West End Line
E	Queens–Manhattan Express	179th Street – Hudson Terminal/Rockaway Park (via Eighth Avenue and Houston Street)	active; all trains now run Jamaica Center to World Trade Center
F	Queens–Manhattan Express	179th Street – Hudson Terminal/Coney Island (via Sixth Avenue)	active; all trains serve Coney Island or Kings Highway
GG	Queens Brooklyn Local	Forest Hills – Church Avenue (via Crosstown Line)	renamed G; trains short turn at Court Square
HH	Court Street Shuttle	Court Street – Hoyt–Schermerhorn Streets	discontinued; tracks repurposed by New York Transit Museum
HH	Rockaway Local	Euclid Avenue – Rockaway Park/Far Rockaway	renamed H, then S; current service runs all trains to Rockaway Park

Following the inauguration of the Chrystie Street Connection, the IND's letter-based system was gradually eliminated. Presently, all lines employ single-letter designations while retaining only the distinction between 8th and 6th Avenues (A, C, E versus B, D, F). Additionally, numbered BMT routes were converted into lettered ones under municipal control to align with IND naming conventions.

Platform lengths

The IND was constructed with platforms longer than those found on the IRT or BMT lines, originally intended to accommodate eleven-car trains. Nevertheless, numerous stations along the IND Eighth Avenue Line between 72nd Street and 163rd Street – Amsterdam Avenue feature platforms measuring exactly . Notable exceptions include 96th Street, which has platforms of , and 81st Street–Museum of Natural History, where the uptown platform extends to while the downtown platform is . Comparable platform lengths of can be found at several IND Queens Boulevard Line stops between Elmhurst Avenue and 67th Avenue.

On the IND Sixth Avenue Line, platforms are even more extended: at 34th Street–Herald Square, the original uptown platform length was , suitable for 12-car trains, whereas the downtown platform measured . Both platforms at 23rd Street are , and the platforms at 47th–50th Streets–Rockefeller Center also measure .

Stations proposed for the IND Second System would have had platforms ranging from to , featuring updated tile designs.

Surviving IND equipment

The Independent Subway System exclusively operated with the R1–9 series, which included models such as the R1, R4, R6, R7/A, and R9. Following their phase-out in the 1970s, twenty cars were preserved: eleven are maintained by the New York Transit Museum and Railway Preservation Corp., while others remain in private collections or are held by additional museums. This preserved rolling stock constitutes an important element of the IND’s historical and operational heritage.

Sources

Books:

Brian J. Cudahy, Under the Sidewalks of New York, revised edition, Lexington, Mass: The Stephen Greene Press, 1988
Joseph Cunningham and Leonard DeHart, A History of the New York City Subway System: The Independent System and City Ownership, 1977
Gerhard M. Dahl, Transit Truths, Brooklyn-Manhattan Transit Corporation, Brooklyn, NY, 1924
Stan Fischler, The Subway: A Trip Through Time on New York's Rapid Transit, Flushing, NY: H & M Productions, Inc., 1997
Herbert George, Change at Ozone Park, Flanders, NJ: RAE Publishing Inc., 1993
Alan Paul Kahn and Jack May, The Tracks of New York, Number 3, New York: Electric Railroaders' Association, Inc., 1977
Frederick A. Kramer, Building the Independent Subway, New York: Quadrant Press, Inc., 1990
Frederick A. Kramer, Subway to the World's Fair, Westfield, NJ: Bells and Whistles, 1991
Robert W. Snyder, Transit Talk, Brooklyn, NY/New Brunswick, NJ/London: New York Transit Museum and Rutgers University Press, 1997

Periodicals:

Electric Railroaders' Association: Headlights Magazine: August 1956; February 1968; February 1973; August 1974; July/September 1977; May/June 1988

Newspapers:

The New York Times (pre-1977), including significant dates in 1929, 1932, 1940, and 1967
Unpublished document from New York City Transit Authority (forerunner to "Facts and Figures"), 1977

External links