Progress of American railroads and railroad technology — 1940s industry promo film.

In step with the march of progress, railroad operating methods improved. The old highball signal gave way in time to the semaphore and to automatic position light signals. The old iron rail was replaced by the modern steel rail with a deep, safe roadbed. Wooden cars gave way to all steel construction. [music] And to the original crudely operated brake was added a new invention, the air brake, which has contributed so much to make your railroad the safest form of transportation. By 1880, many thousand miles of track had been laid. The progress of America and the progress of its railroads became one and the same thing. Electricity was harnessed to the railroad. Tunnels were dug under the Hudson River so trains could go directly to the heart of New York City and Pennsylvania Station became a reality.