Without immigration the US population would be experiencing negative growth. Most European countries are the same. It seems the poorest countries do all the breeding. Imagine a program where you pay women in those poor countries to be sterilized. Give them enough money they can live in comfort the rest of their lives and you have a cold, inhuman solution to over population. In the rich countries people are too busy having fun to have children. I live and work in a middle class environment and hardly anyone has more than one or two children anymore.