Interborough Rapid Transit Company
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 in June 1940, along with the younger BMT and IND systems, to form the modern New York City Subway. The former IRT lines are now the A Division or IRT Division of the Subway.
A New York Transit Museum set of IRT Lo-Voltage motor cars at Mosholu Parkway station
The IRT Powerhouse
An old IRT sign remains at Wall Street station.
Routes of the Interborough Rapid Transit Company, 1924
An elevated railway or elevated train is a railway with the tracks above street level on a viaduct or other elevated structure. The railway may be broad-gauge, standard-gauge or narrow-gauge railway, light rail, monorail, or a suspension railway. Elevated railways are normally found in urban areas where there would otherwise be multiple level crossings. Usually, the tracks of elevated railways that run on steel viaducts can be seen from street level.
Liverpool Overhead Railway, May 1951
NS 93 train on an elevated portion of the line 5 of the Santiago Metro
Two Wuppertal Schwebebahn trains meet above the street
Chicago "L" elevated tracks