Trump certainly demonstrated how surprisingly effective openly voicing xenophobic and racist fears could be in America, but Great Replacement theory is not at all an American or even a recent thing. All of it, everywhere, is just a rehashing of fascist, nationalist tactics. Too many of us mistakenly concluded that these were lessons of history absorbed well enough to insulate society from obviously dangerous and deluded "theories" like this one. Nope.
... He was, of course, also a racist and eugenicist. In 1916, he authored The Passing of the Great Race, in which he claimed the superiority of the "Nordic" race and painted immigrants and Jewish people as "inferior" "social discards" overrunning his city. American "culture" , even at its worse it permeate the world's mindMadison Grant was born into a blue-blooded New York family.