It usually took one generation. Of course immigrants used to (and some still do) make it a point to speak English at home, even if they didn’t speak it well, and taught their kids that America is the greatest country on earth where anyone can be successful. Obama’s commie mother and grandparents and Muslim step-father taught him that America and Western Civilization are evil and the cause of all the suffering in the third world.
The last ice age preserved North America for an advanced civilization not cluttered up by the messes made by all the previous populations in the mideast etc. The number of people, led by Odumbo and his Roids, who seem determined to destroy the opportunity is amazing. And it seems it is going to take a major house cleaning to get back on track.
When in the course of human events————Semper Fi