In my view, the start of the fall was WWII, where we adopted the fascist scientists and agents and brought them into Western civilization to head our agencies in order to counter the Soviet Union.
It actually goes back farther, when the bankers colluded by creating federal reserves in every country to control the economies.
One can argue it predates that, to the aftermath of the Civil War. And some will argue it was before that, in the 1840’s. Others can Argue it was Andrew Jackson’s Admin who started the decent……..
“Our Germans are better than their Germans”