I find it interesting where he says "we wouldn't have become a superpower without the contributions of immigrants", rather than consider that almost every American living today had immigrant ancestors.
At which point does he draw the line of immigration? At which date does he (or any American) consider himself "American" rather than an immigrant?
I suppose at the point where one feels closer to the "generic" American values/culture than to that of your forebears. I think it's the truest definition, however it is often hard to prove/demonstrate, so the arbitrary definition "have be born in this country" is used instead.
so the arbitrary definition "have be born in this country" is used instead
That hardly seems arbitrary -- it's what the word means. If you were born outside the country then you have immigrated, therefore you are an immigrant.
Well it may seem a bit arbitrary to those who grew up in the U.S. but were born elsewhere (or even to those who were born in the U.S. but grew up culturally isolated).
At which point does he draw the line of immigration? At which date does he (or any American) consider himself "American" rather than an immigrant?