There is simply little debate that immigration cannot stop or even dramatically slow population aging in low-fertility countries like the United States at current levels or even with a substantial increase. The only way immigration could have a very big impact on the age structure of the United States is if it were historically unprecedented and constantly increasing. There are several reasons for this: First, immigrants age like everyone else over time. Second, their fertility is not much higher than that of the native-born and is declining. Third, immigrants arrive at all ages and add to the population through the age structure. Fourth, when the children of immigrants born in the United States enter the labor force, a significant share of their immigrant parents will have reached retirement age, thus increasing the number of workers and retirees.
Academic Demographers on Immigration and Aging
Oxford demographer David Coleman noted of immigration:
It is already well known that it can only prevent population aging to unprecedented, unsustainable and growing levels of influx.
In an important 1992 article in Demography, economist Carl Schmertmann showed that mathematically:
The constant influx of immigrants, even at relatively young ages, does not necessarily rejuvenate populations with low fertility. In fact, immigration may even contribute to the aging of the population.
Thomas Espenshade, the former chair of Princeton’s sociology department and director of its graduate program in population studies observed several years ago:
It becomes apparent that the effect of alternative immigration levels on the age structure of the population is small, unless we are willing to accept a volume of US immigration of historic proportions. … Immigration is an awkward and unrealistic policy alternative to offset a domestic labor shortage or to correct a perceived imbalance in the retiree/worker ratio in the United States.
Nicholas Eberstadt, Henry Wendt Professor of Political Economy at the American Enterprise Institute:
[I]immigration cannot maintain a young demographic structure for a country in the long term… arithmetic does not work.
Census Bureau projections. The U.S. Census Bureau said as part of its population projections in 2000 that while immigration may have a short-term impact, it is a “very inefficientmeans increasing the share of the population of working age in the long term. The most recent population projections from the Census Bureau show a total US population in 2060 of 376.2 million in a “low immigration scenario” and 446.9 million in a “high immigration scenario” – a difference of 70.7 million (table np2017-a). Yet, the share of the working age population (18 to 64) in 2060 would be 56.3% in a low immigration scenario and 57.4% in a high immigration scenario, a difference of only 1 .1 percentage point (table NP2017-D%). So the impact of 71 million additional US residents as a result of immigration is quite modest.
Immigration Studies Analysis Center. Using the U.S. Census Bureau’s fertility and mortality assumptions and varying their migration assumptions, an analysis by the Center for Immigration Studies shows the relatively small impact of immigration on the aging United States over the next half century. An interesting conclusion from our projections is that if we wish to use immigration to maintain the current share of the working-age population, we would need to admit five times as many immigrants as are currently arriving, bringing the total population at 706 million, which is more than double its current size. The immigrant population would rise to 257 million in such a scenario. This equates to three quarters of the entire US population in 2022. We also found that even doubling the current level of immigration still has only a modest impact on the share of workers.