A Division (New York City Subway) in the context of "IRT Broadway–Seventh Avenue Line"

The Interborough Rapid Transit Company (IRT) was the private operator of New York City's original underground subway line that opened in 1904, as well as earlier elevated railways and additional rapid transit lines in New York City. The IRT was purchased by the city on June 12, 1940, along with the younger BMT and IND systems, to form the modern New York City Subway. The former IRT lines (the numbered routes in the current subway system) are now the A Division or IRT Division of the Subway.

The IRT Flushing Line is a rapid transit route of the New York City Subway system, named for its eastern terminal in Flushing, Queens. It is operated as part of the A Division. The Interborough Rapid Transit Company (IRT), a private operator, had constructed the section of the line from Flushing, Queens, to Times Square, Manhattan between 1915 and 1928. A western extension was opened to Hudson Yards in western Manhattan in 2015, and the line now stretches from Flushing to Chelsea, Manhattan. It carries trains of the 7 local service, as well as the express <7> during rush hours in the peak direction. It is the only currently operational IRT line to serve Queens.

It is shown in the color purple on station signs, the official subway map, and internal route maps in R188 cars. Before the line was opened all the way to Flushing in 1928, it was known as the Corona Line or Woodside and Corona Line. Prior to the discontinuation of BMT services in 1949, the portion of the IRT Flushing Line between Times Square and Queensboro Plaza was known as the Queensboro Line. Since the mid-2010s, the line's signal system has been converted to an automated system.

The 7 Flushing Local and <7> Flushing Express are two rapid transit services in the A Division of the New York City Subway, providing local and express services along the full length of the IRT Flushing Line. Their route emblems, or "bullets", are colored purple, since they serve the Flushing Line.

The 7 operates 24 hours daily between Main Street in Flushing, Queens and 34th Street–Hudson Yards in Chelsea, Manhattan, making all stops along the full route. Additional service operates along the full route and makes express stops in Queens between Mets–Willets Point and 74th Street–Broadway during rush hours in the peak direction instead of making all stops; these trains labeled as <7> Express trains. Super express service operates after special events at Citi Field or the USTA Billie Jean King National Tennis Center in the southbound direction only.

The IRT Lexington Avenue Line (also known as the IRT East Side Line and the IRT Lexington–Fourth Avenue Line) is one of the lines of the A Division of the New York City Subway, stretching from Lower Manhattan north to 125th Street in East Harlem. The line is served by the 4, ​5, ​6, and <6> trains.

The line was constructed in two main portions by the Interborough Rapid Transit Company (IRT), a private operator. The first portion, from City Hall north to 42nd Street, was opened between 1904 and 1908, and is part of the first subway line in the city. The original subway turned west across 42nd Street at the Grand Central station, then went north at Broadway, serving the present-day IRT Broadway–Seventh Avenue Line. The second portion of the line, north of 42nd Street, was constructed as part of the Dual Contracts, which were signed between the IRT; the Brooklyn Rapid Transit Company, via a subsidiary; and the City of New York.

The IRT Jerome Avenue Line, also unofficially known as the IRT Woodlawn Line, is an A Division New York City Subway line mostly along Jerome Avenue in the Bronx. Originally an Interborough Rapid Transit Company-operated route, it was built as part of the Dual Contracts expansion and opened in 1917 and 1918. It is both elevated and underground, with 161st Street–Yankee Stadium being the southernmost elevated station. The line has three tracks from south of the Woodlawn station to the 138th Street–Grand Concourse station. The Woodlawn Line also has a connection to the Jerome Yard, where 4 trains are stored, just north of the Bedford Park Boulevard–Lehman College station.

The 6 Lexington Avenue Local and <6> Pelham Bay Park Express are two rapid transit services in the A Division of the New York City Subway. Their route emblems, or "bullets", are colored forest green since they use the IRT Lexington Avenue Line in Manhattan. Local service is denoted by a (6) in a circular bullet, and express service is denoted by a <6> in a diamond-shaped bullet. On the R62A rolling stock, this is often indicated by LEDs around the service logo to indicate local or express service to riders. The LEDs illuminate in a green circle pattern for 6 local trains and in a red diamond pattern for <6> trains.

The 6 operates 24 hours daily between Pelham Bay Park in the Bronx and Brooklyn Bridge–City Hall in Lower Manhattan, making all stops in Manhattan. Additional service short turns at Parkchester in the Bronx during weekday rush hours and middays and does not operate to or from Pelham Bay Park; during this time, 6 trains that originate and terminate at Parkchester make all stops in the Bronx, while trains that serve the full route make express stops in the Bronx between Parkchester and Third Avenue–138th Street in the peak direction and are labeled as <6> Express trains; when the <6> Express is not running, 6 trains originate and terminate at Pelham Bay Park and make all stops in the Bronx.