Calling themselves "alt-right" as a way to appear more mainstream, their views are essentially the same as White-supremacist groups throughout American history: That Whites who trace their ancestry to Western and Northern Europe are the superior race, and the only true Americans. The presence of Trump, first with his "birtherism" trolling, to his presidential campaign, to his election, has engendered a feeling of vindication for groups that were previously confined to the dark fringe of the web. And they now feel comfortable making their presence known:
Update: The above piece, which was originally commissioned to accompany the opening illustration, ended up being used for a different post that's online now: defining the various terms used to refer to the groups comprising the "alt-right." Thank you so much to my wonderful AD, Ivy! And to give credit where credit is due, the visage of Trump was from a photo taken by Gage Skidmore.