How will another 220,000,000 Americans affect you? Professionally? Personally? How about the environment? These are the preliminary questions raised by a recent article in The Economist. In this editorial I will try to sketch a way to look at the issues. The gist of The Economist's article is that America and Europe show strong signs of diverging demographically, after many years of moving in tandem. Before 1980, both were dropping so far in fertility rates (the number of children born to each woman) that both were below the replacement level of about 2.1 children per woman.