Much of the credit for America's vibrantly growing population goes to immigration, currently adding about 1.2 million to the populace annually. Moreover, many of these immigrants tend to be of child-bearing age, and most have higher birthrates than native-born Americans. That's a positive for the economy because a larger populace, if sufficiently trained, creates a larger local market and more workers to produce more goods and services. Countries with stagnating population growth have to depend more heavily on productivity growth -- a much chancier path to prosperity for mature economies. That's why Japan, an immigration- averse nation that just announced that its population would likely fall this year for the first time in history, is likely to have a hard time maintaining its economic stature as its population quickly ages.
Unfortunately, there's also a grim message from the PRB study: Much of today's population growth is occurring in parts of the world that can ill afford the increase. Africa will account for fully one-quarter of the earth's population rise this year. And if current trends continue, three African nations (the Democratic Republic of the Congo, Ethiopia, and Nigeria) will be among the world's 10 most populous by 2050 -- each bigger than Russia, Japan, or any European country. That's why bringing such poor countries into the world's economic mainstream is so essential. As China and India have shown, for even populous countries that embrace tough market reforms, no destiny need be preordained.