Many refugees (mostly Jewish) from Vienna went to Manhattan, or the Manhattan Project. A few, like Freud or Popper, stopped in Britain, but many passed through to New York. Bernays (Freud's nephew) used his uncle's psychological insights to invent propaganda, marketing, advertising and PR. Others invented atomic and hydrogen bombs (probably less devastating than therapy and ads :) Some were Soviet atomic spies that reported back to the USSR.
Much of American pre-war/post-war intellectual life is due to European refugees. It's interesting to posit what might have happened without the influx.