The Prelinger Archives is a vast and wonderful collection of “ephemeral” films: documentaries, educational films, advertisements, and industrial footage, all in the public domain. Rick Prelinger, founder of the Archives, shares one of his favorites, a promotional film for AT&T, made in 1941. Although the first lasting transatlantic cable was laid in 1866, it's not hard to feel a thrill as the film's narrator compares the expansion of AT&T's network to the explorers who made their way to the American west.
Rick Prelinger: Long Distance! is a hymn to the combined efforts of communication engineers and the "alert young women" who provide the "watchful feminine presence at the switchboard." It's also a great example of a lost genre: poetic documentary, beautifully shot, elegantly blending music and narration. At the same time, it's also about geopolitics, linking the buildout of U.S. long distance infrastructure with the spread of U.S. influence throughout the North American continent, and implicitly showing the relationship between communications networks and state power. I also like the unusual end title.
For more films from the Prelinger Archives, see http://www.archive.org/details/prelinger.