The National Film Registry is the United States National Film Preservation Board's selection of films for preservation in the Library of Congress. The Board was established in 1988. Each year, 25 "culturally, historically, or aesthetically significant films" are preserved, to increase awareness for its preservation. To be eligible for inclusion, a film must be at least ten years old but it is not required to be feature-length, nor is it required to have been theatrically released.
Source: https://www.loc.gov/programs/national-film-preservation-board/film-registry/complete-national-film-registry-listing/
