The Economist on 300 million Americans (sub req’d):
Rapid growth may cause environmental problems, but it will greatly slow the pace at which America ages. Whereas in the EU by 2050 there will be fewer than two adults of working age for every person over 65, the proportion in America will be less scary, at almost three to one. The problems of growth, says Mr Klineberg, are easier to deal with than the problems of decline.
Can the world cope with a relentlessly expanding America? Many non-Americans will shudder at the prospect, but which alternative superpower would they prefer? China? If demography is destiny, they will not have to find out what a Chinese hyperpower looks like: the fertility rate in China is only 1.7, and there are almost no immigrants.