Every year since 1989, the US National Film Preservation Board selects 25 American films for preservation, based on the films' historical, cultural, and aesthetic contributions--this list is called the National Film Registry. This is the current list of selected films, as of 2022. (The next round of selections won't happen until December 2023, so this will be current for the next several months.)
As of posting date, 3/19/23, I've seen 295 of these, which is 35%.