El Train

As a solution to Manhattan's rapid population growth and street congestion in the late 1800s, railroad companies decided to better serve their passengers by elevating the trains above ground. Originally, four elevated lines ran the length of Manhattan, but after complaints about the trains blocking light and emitting extremely loud noise, they suffered from a decrease in ridership. The elevated trains that ran along Second, Sixth and Ninth Avenues were all demolished between 1939 and 1942. The one line that stood its ground for a bit longer was the Third Avenue El, which was constructed between 1875 and 1878 and ran from South Ferry to Chatham Square before closing for good in 1955.
See the final days of the El train