"There are many ways to define "disturbing," but Merriam-Webster lists four traits that give us a good place to start when working with the term. It means anything from causing annoyance, embarrassment, anxiety, or worry to causing agitation or uncomfortable feelings.
In this case, there are certainly a good many films across the spectrum that embody these traits, but only a handful stand out as the most disturbing. Even so, limiting one's scope to examining only the most disturbing American films grants an even smaller list.
What follows is a ranking for the 10 most disturbing American films, and it includes a variety of genres in order to address the full range of meaning regarding what truly "disturbs" the spectator. No doubt, some of the films below made you irate or need to walk out of the room. Maybe they made you scream in terror or cry with grief. In the end, they left you disturbed, and that's their greatest feature."