Not really. From 1925-1965 mass immigration was cutoff with an annual rate of about 250,000. Illegal immigration, though still a problem did not start to become this bad until the seventies and eighties but really exploded in the last decade.
The bottom line is American citizens did most of the work of the country and in fact in those areas not yet invaded continue to do so.
That's fine, but you did stil have the same immigrants from the early 1900s, and their children. These families would likely not rise to great education and prosperity until the second generation of Americans was born.
Oh, and by the way, Reagan, with amnesty programs and all, wuz the best. ;)