We would be so much smarter to encourage Americans to have more children than to try to assimilate the poorest Mexicans. Our society would be more cohesive. We were all propagandized into limiting our families to two children, and that could certainly change. I am 62 now, but I would rather have had three or four children than have to put up with all these foreigners everywhere I turn. (And, no, I don't mean more welfare).
Having more children is not the answer when these children will not mow the neighbors lawn for the astronomical amount of $5.00 an hour because he is given everything anyways!
I think populationist propaganda had less to do with it than hard economic realities. I strongly advocate returning per-child deductions to the real (inflation-adjusted) value they had when the income tax was introduced, instead of treating the decision to have children as essentially equal to the decision to have tropical fish.