The New York Pneumatic Railroad (NYPR for short) is the name of the abandoned 19th century subway line running beneath New York City. It was found by the Ghostbusters after uncovering one of its air-shafts on First Avenue, and it is revealed that this railroad is where the dreaded River of Slime is first discovered.
Details about the Pneumatic Transit system are scarce, save that it was constructed in 1870 A.D., and then it was later abandoned for unknown purposes. Only one station on the system is seen, called Van Horne, which lies beneath First Avenue, and can be accessed via an air shaft from the surface or via a service tunnel leading from the modern subway system. No other stations are mentioned or seen.
Van Horne and the entire Pneumatic Transit system were constructed in the 1870's by inventor Alfred Ely Beach, and was referred to as the New York Pneumatic Rail Road (NYPRR). The air-shaft opened by the Ghostbusters bore these initials on a man-hole cover covering up the shaft. Egon Spengler explains to Peter Venkman it was an experimental subway system that was to use fan-forced air-trains, trains blown along the tunnels by gigantic fans, and that the line was an experiment in providing a new, novel means of mass transit.
Ray Stantz noted to himself the NYPR was a shortline railroad in use before the subways. Shortlines are small to mid-sized and are used to link up two industries, interchange traffic with a larger railroad, and tourist transportation.
For unexplained reasons, the system was not a success and was subsequently abandoned, its tunnels being sealed up and forgotten by the outside world.
Sometime after the First World War, the Gozer Worshippers created the Psychomagnotheric Slime, which somehow flooded the abandoned subway tunnels and began flowing steadily through them as a river, leading towards the Manhattan Museum of Art to provide power to their god Gozer, but it was later used by the spirit of the 16th century Carpathian despot Vigo whose evil spirit was residing in a painting there.
Exactly how the slime first entered the tunnels, or whether the subway once had a station close to the museum, is never explained.
- In Ghostbusters: The Video Game (Realistic Versions), some work was done on a level featuring the Pneumatic Railroad and the River of Slime but it was never used for the game.
- In the IDW Ghostbusters comics, Egon Spengler reconignized and also referred the abandoned subway by its another name "New York Pneumatic Railway".