Washington ? Crank up the volume to 11 forever: “This is Spinal Tap” will be preserved by the National Film Registry.

The mordant 1984 “mockumentary” of rock star pretensions joins the children’s classic “The Black Stallion,” sci-fi groundbreaker “Alien,” and 22 other films selected this year for preservation by the Library of Congress.

Also included are “All My Babies,” a 1953 film made to educate midwives in the South, and “Through Navajo Eyes,” a 1966 series of documentaries on an Indian tribe.

The registry now contains 350 films. Making the list helps “ensure that the film is preserved for all time,” the library said in a statement.

“The selection of a film, I stress, is not an endorsement of its ideology or content, but rather a recognition of the film’s importance in American film and cultural history and history in general,” Congressional Librarian James H. Billington said.

“Spinal Tap” was not the first satire to use the documentary form to needle its subject, but with its would-be geniuses delivering bloated confessionals and staging “events” that go hilariously awry, it has become the template for others. “The Country Bears,” a Disney outing this year, was in part an homage to “Spinal Tap.”

In one memorable moment, rock auteur Nigel Tufnel, played by Christopher Guest, explains his pride and joy — an amplifier with dials that reach “11” — to a documentarian played by the film’s real director, Rob Reiner.

“It’s one louder, isn’t it? It’s not 10. You see, most blokes, you know, will be playing at 10. You’re on 10 here, all the way up, all the way up, all the way up, you’re on 10 on your guitar. Where can you go from there? Where?”

“Alien,” the 1979 Ridley Scott film, veered cinematic science fiction sharply away from the sunny optimism of “Star Wars,” “Star Trek” and “Close Encounters of the Third Kind,” and restored the threat of the unknown to space exploration. It also established what was then almost unknown: the strong female sci-fi lead, played by Sigourney Weaver.

Other films included are Vincente Minnelli’s “The Bad and the Beautiful,” a scorching 1952 examination of how Hollywood exploits and discards talent, starring Kirk Douglas; and to “From Stump to Ship,” a 1930 documentary on logging in Maine.

There’s “Fuji,” 1974, Robert Breer’s experimental travelogue on a train trip in Japan, and “The Endless Summer,” a 1966 documentary about two surfers hoping to catch the perfect wave. “The Black Stallion,” Carroll Ballard’s 1979 adaptation film of the Walter Farley children’s classic, is also on the list.

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One of the selections is more than a century old: “The Star Theatre” records the 1901 demolition of a New York theater.

Also on the list is a film version of Oscar Wilde’s play “Lady Windermere’s Fan,” made in 1925, “Boyz N the Hood,” John Singleton’s 1991 account of Los Angeles gang life, and “Melody Ranch,” 1938, which starred Gene Autry, the first singing cowboy.

Emphasizing the need to preserve film, Billington said that half the movies produced before 1950 and between 80 percent and 90 percent of those dating before 1920 have been lost to chemical deterioration.