The 2 train is the more important of the two 7 Avenue Express Lines, and the longest IRT route. Its last stop is also the most northern point on the subway system, with the longest subway ride with a connection being taking the 2 train from 241 Street to Fulton Street and transferring to the A train there out to Far Rockaway: a distance of more than 38 miles!
The 2 train operates at all times between Wakefield-241 Street and Flatbush Avenue, with trains operating local in Manhattan between Midnight and 5:00am (ends at 6:00am on Sunday mornings) and Express in Manhattan at all other times, service is always local in the Bronx and Brooklyn. 1 train service still operates during late nights, but 2 trains run local to provide more frequent service at the busy local stations in Manhattan and simplify any late-night track work. During late nights 2 trains make 61 stops on their scheduled at 1 hour and 50 minute run, just one less than the A trains 62 when it runs local overnight. During regular service trains makes 49 stops, more than the A train.
At the beginning and ends of rush hours some trains run to and from New Lots Avenue (these aren’t advertised on the subway map, but are on the line schedule). This is to allow trains to access the only IRT yard in Brooklyn, the Livonia Yard. These trains include one 7:23am rush hour departure, and five trains that terminate at New Lots Avenue at the end of the rush hour between 8:52am and 10:48am. These same trains leave New Lots Avenue again between 3:42pm and 5:09pm to provide more rush hour service. All 2 train service ran to and from New Lots Avenue before 1983, although over the previous decades since the line was completed in 1918 service in Brooklyn flipped-flopped a lot between New Lots Avenue and Flatbush Avenue (at times it was time of day dependent).
For being such an important subway line, it only has one stop, its first stop at Wakefield-241 Street stop, that isn’t shared with any other subway lines. The rest of its track — except for the 149 Street tunnel between Manhattan and the Bronx — is shared during peak direction rush hours at a minimum with 5 trains in the Bronx — although these same trains skip 7 stops that are only serviced by 2 trains during peak direction rush hours — and the Nostrand Avenue subway portion in Brooklyn, and the 3 train in Manhattan and the start of the route in Brooklyn. The subway line didn’t have any stops to fully call its own before 1995 when some rush hour 5 trains still extended to Wakefield-241 Street, not terminating one stop short at Nereid Avenue for better access to the 239 Street train yard.
Operationally it is operated with the 5 train, not the 3 train, with trains used on the two routes interchangeably and sharing the 239 Street, Unionport and East 180 Street train yards. These two lines used to exclusively run with Redbird cars until the R142 New Technology trains were introduced and replaced the redbirds, the last non-stainless steel subway cars.
When the R142 subway cars were delivered with electronic strip maps some had 2 train stops (except for late night stops) and some 5 train stops. Unfortunately, as the train cars were used interchangeably it was not uncommon to be on a 2 train with the strip maps out of service because it was using a R142 car with 5 train strip maps. Around 2015, a pilot program combined the two strip maps which was made permanent and now the R142 cars assigned to 2 and 5 trains have express stops on both Lexington Avenue and 7 Avenue to show all stops on both routes (there are just enough lights on the strip maps for this).