Believe it or not, you can nominate films to the Film Registration Board for preservation in the Library of Congress's National Film Registry; they actually pay attention.
Shockingly, Philip Kaufman is among the filmmakers with no films on the list (that he directed–as a writer he is represented by "Raiders of the Lost Ark" and "The Outlaw Josey Wales"). Apparently, "it is not unusual for it to take many years of Film Board discussion before a title is added to the Registry, if ever," according to one Library of Congress source.
The good news: we can all lobby to nominate worthy films for the voting board to consider. According to Kaufman biographer Annette Insdorf, the Kaufman film with the best shot is likely "The Right Stuff," followed by "The Unbearable Lightness of Being."
There is a process. Write before the September 15 deadline to the Board (which will vote in October or November) c/o Donna Ross, Assistant to The National Film Preservation Board, The Library of Congress: firstname.lastname@example.org.
More on the NFR is here.