The National Film Registry allows anyone and everyone to nominate 50 films for selection every year (website and details here: https://www.loc.gov/programs/national-film-preservation-board/film-registry/nominate/). Deadline is August 15. Selections are announced on or around December 15.
This is the third year I've made nominations. There's quite a bit of overlap from past years--I will continue to nominate "Rabbit of Seville" and "Repo Man" until I die, or until the NFR selection committee comes to their senses, whichever comes first.
List image: Emilio Estevez and Harry Dean Stanton in the aforementioned "Repo Man"
And yeah, I just noticed that "I Am Not Your Negro" isn't eligible--films need to be at least 10 years old.