Thanks MarvinStinson.
That FDR tapped Ales Hrdlicka, and that the latter had racial superiority views, was a little bit surprising to me -- Ales Hrdlicka began his career advocating in favor of PreColumbian contact as the explnation for megalithic structures and large moundbuilding. He then made a strong 180 and is literally the godfather of the isolationist view that prevails today as Clovis-First-and-Only. Isolationism has a political appeal of course, and it could be argued has roots in xenophobia and racial superiority. Columbus, he was the first to come by boat, the ancestors of Precolumbian tribes, they came on foot, and only did it once.
In Hrdlicka's time, the view was that human presence in the Americas was only 3000 years old. That view died hard, but not as hard as Clovis-First-and-Only.
That said, the worst barrier to Jews escaping Europe was the notorious British White Paper, which severely restricted Jewish immigration to Palestine as an appeasement to the Arabs.