Prince checks in to the Library of Congress

Prince in his "Purple" breakthrough. (photo courtesy Warner Bros.)

It means forever, and that's a mighty long time.

The Library of Congress has added Prince and the Revolution's "Purple Rain" soundtrack to its National Recording Registry -- an elite group viewed as historical treasures and worthy of preservation for generations to come.

With something like 26 million copies of "Purple Rain" sold worldwide, you'd think preserving it wouldn't be a problem. But still, this is a big deal. Ten years since the program began, only 350 recordings have been chosen -- not just music but speeches, radio skits, poetry, even a Lake Michigan foghorn.

A total of 25 recordings were added in this year's round, announced Wednesday, including "Green Onions" by Booker T. and the MG's (which joins an actual speech by Booker T. Washington on the list).

All in all, this year's list is pretty funky, with cuts or albums from Bo Diddley, Parliament, Donna Summer and the Sugarhill Gang. Other musical greats include Dolly Parton, Leonard Bernstein, Stan Kenton and the Grateful Dead (a soundboard recording, natch).

Here's this year's list:

1. Edison Talking Doll cylinder (1888)
2. "Come Down Ma Evenin' Star," Lillian Russell (1912)
3. "Ten Cents a Dance," Ruth Etting (1930)
4. "Voices from the Days of Slavery," Various speakers (1932-1941 interviews; 2002 compilation)
5. "I Want to Be a Cowboy's Sweetheart," Patsy Montana (1935)
6. "Fascinating Rhythm," Sol Hoopii and his Novelty Five (1938)
7. "Artistry in Rhythm," Stan Kenton & and his Orchestra (1943)
8. Debut performance with the New York Philharmonic, Leonard Bernstein (November 14, 1943)
9. International Sweethearts of Rhythm: Hottest Women's Band of the 1940s (1944-1946)
10. "The Indians for Indians Hour" (March 25, 1947)
11. "Hula Medley," Gabby Pahinui (1947)
12. "I Can Hear It Now," Fred W. Friendly and Edward R. Murrow (1948)
13. "Let's Go Out to the Programs," The Dixie Hummingbirds (1953)
14. "Also Sprach Zarathustra," Fritz Reiner and the Chicago Symphony Orchestra (1954, 1958)
15. "Bo Diddley" and "I'm a Man," Bo Diddley (1955)
16. "Green Onions," Booker T. & the M.G.'s (1962)
17. "Forever Changes," Love (1967)
18. "The Continental Harmony: Music of William Billings," Gregg Smith Singers (1969)
19. "A Charlie Brown Christmas," Vince Guaraldi Trio (1970)
20. "Coat of Many Colors," Dolly Parton (1971)
21. "Mothership Connection," Parliament (1975)
22. Barton Hall concert by the Grateful Dead (May 8, 1977)
23. "I Feel Love," Donna Summer (1977)
24. "Rapper's Delight," Sugarhill Gang (1979)
25. "Purple Rain," Prince and the Revolution (1984)