Immigrants the Key to Continued U.S. Population Growth

The U.S. Census Bureau just released its latest projections of the U.S. population. This is called the 2017 series and, like the previous 2014 series, it builds on the base of the 2010 census. Of particular note, of course, is that despite the gradual aging of the U.S. population (which is mainly what has been hyped in the press), we are projected to continue growing in number, from 326 million this year to 404 million by 2060. This is true even though the fertility rate remains low, largely because of the projected continued net immigration into the country. Todd Gardner very astutely picked up on this particular graphic from the Census Bureau's news release about the projections:

Notice that if we assume a continuation of approximately one million new immigrants per year, then by 2030, the immigrants will make a bigger contribution to U.S. population growth than will natural increase (the excess of births over deaths). And, of course, since migrants tend to be young adults, they also contribute more to the births than to the deaths during the first several years after their arrival. What could change those ratios? Obviously a change to immigration policies could slow down the flow of migrants. An improvement in the death rate among the very young and the elderly (the ages where the U.S. lags behind other rich countries) would push up the rate of natural increase, as would an increase in the birth rate. The latter is probably the least likely of those three scenarios.