The people who were most American by birth, and who had the most to do with managing America, gave themselves a literature which had the least to say about the real phenomena of American life, most particularly the accelerated rate, the awful rate, of growth and anomaly through all of society. That sort of literature and that sort of attempt to explain America was left to the sons of immigrants who, if they were vigorous enough, and fortunate enough to be educated, now had the opportunity to see that America was a phenomenon never before described, indeed, never before visible in the record of history. There was something going on in American life which was either grand or horrible or both, but it was going on—at a dizzy rate—and the future glory or doom of the world was not necessarily divorced from it… 

- Norman Mailer, from Cannibals and Christians (1965)

Miloš Forman, the Czech film director, lived and worked in the former Czechoslovakia until 1968, but once in America, made some of the most quintessential of American films, including One Flew Over the Cuckoo's Nest, Hair, Ragtime, The People Vs. Larry Flynt, and the Andy Kaufman bio-pic, Man in the Moon.  The point being we need immigrants to explain our country to ourselves.