From The Atlantic's coverage of the effort last year:

"Somebody will recognize an actor, somebody will recognize an automobile," said Ben Model, a historian and pianist who will be playing musical accompaniment to many of the silent films on display. "People are looking things up frantically on iPads, calling out, 'Okay, between 1923 and 1926 so and so was at this studio.'"

You can browse through the Library's complete database of silent films, which details the 11,000 films made between 1912 and 1929, including the 3,300 that are known to exist. Here's a graph showing films lost (red) versus those that are still around (blue), based on what year they were made:

Library of Congress

For this year's screening, films come from the library's own collection of unidentified movies, along with reels from the George Eastman House, the UCLA Film & Television Archive, EYE Film Instituut Nederland in Amsterdam, Royal Belgian Filmarchive, USC SCA Hugh M. Hefner Moving Image Archive, Lobster Film Archive, and the Newsfilm Library at the University of South Carolina. (Most screenings are free to attend but you have to register by July 1.)

And though many historians have accepted the dismal state of preservation in early film, there's optimism that as more films are catalogued, more previously forgotten works will emerge—either from private collections or from other countries.

Already, the Library of Congress has found more than 800 American-made silent films in overseas collections. In the past decade, there has been a "groundswell of discoveries of silent features that had been thought lost," especially as archives take steps to identify unmarked reels.

"It can be argued that no films are lost—they just haven’t been found yet," wrote David Pierce in the Library's preservation report last year. It's a lovely thought, but perhaps—and Pierce says as much—an overly romantic one. While some 100-year-old nitrate film still exists, much of it has already deteriorated badly.

Of course, once you know what you have, you get a clearer sense of what you're still looking for.

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