After looking at all the population projections prepared by the United Nations, Oxford demographer David Coleman has concluded, “There are no feasible migration solutions to the age-structure change and its effects on social security.” Coleman and others have pointed out that immigration can prevent population decline — that is, it can add a lot of people to the country — but it does not significantly change the age structure in the way that many immigration advocates seem to imagine. If we wanted to use immigration to offset population aging, the level necessary would have to be truly enormous.
A recent paper I coauthored based on the most recent Census Bureau population projections examined the impact of immigration on the nation’s age structure. Assuming current levels of immigration continue, the latest projections indicate that the total U.S. population will reach 404 million in 2060 — 79 million larger than in 2017. Future immigrants and their descendants account for nearly all (75 million) of the increase. Under this scenario, 59 percent of the population will be working-age (16 to 64). By contrast, in a zero-immigration scenario, 57 percent of the population would be working-age in 2060. More realistically, if immigration were limited to half of the expected level, 58 percent would be working age.