Just saw this thread and wanted to revive it. At the same time, I am trying to formulate a response that isn't totally banal.
There is an forthright comparison that most usually think about when masks are mentioned, which is theater. Originally, in Greek plays, masks were employed and the faces of actors were hidden. The interesting thing about masks is that their connection to Greek theater was abrupt, occurring around fifth century B.C. as an experiment to obtain
opsis — to make the performance visual. But, because the visual of the mask deprives the actor of a regular performance, they must make use of greater energy. They must raise their voice, or become an actor by the skill of a loud voice. They must move with a vigorous energy, which is something incomparable to our time where people's voices, facility of language, and theatrical movements are blunted. The element of the mask, a an experiment, provided the theater a mighty spectacle if it succeeds. Tragedy, as Aristotle said near the end of Poetics, does not necessitate movement or gestures of the masked actor; if great enough, it could be read aloud in silence and garner a similar effect amongst an audience. The puzzling nature of the mask, then, was probably what led Nietzsche to say that all the masked tragic heroes are nothing but Dionysus revealed. Masks were employed and men specialized in the task made them sometimes for war, but the real spark was lit when the mask was placed upon the actor's face.
The examples you mention are difficult (which is good & confirms you're onto something) since they span the entire lifespan of America. Since I am more than a little exhausted at the moment, I will restrict myself to post-1910s America and why they might like adopting masks. Certainly, your KKK example will fit into this considering its vast reformation after D.W. Griffith. The point I would make, if restricted only to the post-1910 timeframe, would be that there is a merging of theatrical talents into our own perception. The silent film actors were similarly restricted as the Greek actors were, except that they could not be heard. They must, therefore, gesticulate and move in exaggerated ways to capture the attention of the audience. In the process, there's an intense concern about the face, since the absence of sound is a totally new element. We are, to some extent, visually trained to accept the close-up of an actor's face due to these origins. It should strike us as weird, since the camera places us in the closest possible proximity to the actor's face and permits us to forget his surroundings. Imagine if an actor in Shakespeare's time, to show his surprise, leaned over the stage and showed the audience his shock. It's a bit of a loaded example but you can see how this would break a pattern in the play. Since we are further and further inundated with the face, it should follow that we are concerned about
expressions: how they function, what variety could we show through them, and so on. What's commonly considered good acting today in America is usually extreme emotional reactions such as crying or screaming, and what Americans tend to fear are the expressionless faces.
[Image:
https://i.ibb.co/gRdWfkW/aerith.png]
"Uncanny Valley" is sometimes touted as a scientific explanation for the horror people feel towards the inhuman sight, but you have to wonder if that's because we
naturally had this fear all along or if we're so overexposed to certain facial expressions that this should appear frightening. I've never felt any emotion from seeing this image but a lot of people tend to feel deep fear. The daguerreotype, the invention that exposed Americans to the pictured face, had freaked people out in another way. You can see this in Hawthorne's House of the Seven Gables where Phoebe Pynchon speaks to the daguerreotypist Holgrave. She mentions to him that the faces she sees in the photos scare her, and his reply is that their faces reveal their true character. This is where I might sound convoluted. On one hand, there is an oversaturation of the face, and on the other a persistent disturbance with it. The daguerreotype invites a kind of fear or disturbance, but with the spectator of silent films or films immediately after with sound, there's a love for visual expression. When people are this conflicted over this visual tendency, masks can serve both responses. The expressionless mask invokes fear for the visually trained American and the mask can also be a thing which people can collectively wear, in the case of the Klan (or, more innocently, Halloween). It's this element of expression that managed to be invited through photography and film, and I'm not really sure if it was intentional.
But there's clearly much more going on here, going far back as the Tea Party and Washington Irving's Sleepy Hollow. I just wanted to write this out and see if anyone wants to add onto this. I also restricted myself to masks, not costumes in general, so there's even more room for interpretation here. Oh, and while I'm about to finish up, I realized I forgot to mention the elephant in the room:
[Image:
https://i.ibb.co/rwwkWTr/blackface.png]
