Population Growth . . . With and Without Immigration
In 2006 Joel Garreau wrote “300 Million and Counting” in the Smithsonian. It was then we were at a replacement rate of 2.01. The nation was barely replacing itself. November 20, 1967, the population of the United States passed 200 million. It had taken ~29 years to add 100 million more people to the US population. In 2024, the replacement has dropped to 1.6. Many of the latest citizens are immigrants.
Some say Automation will lessen the blow of a decreasing population.
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U.S. Demographic Projections: With and Without Immigration — Penn Wharton Budget Model
Key determinants of the future size and composition of the population are fertility, mortality, and net immigration rates. Person attributes including race, gender, and education among others.
The Penn Wharton Budget Model’s microsimulation is based on calibrating and projecting more than 60 U.S. demographic variables. Variables such as age, gender, race, marital status, education, family size. Included is region of residence, immigration, legal status, etc. using micro-data on the United States population. The data is from various sources including the Census Bureau. The Centers for Disease Control, the Bureau of Labor Statistics, the University of Michigan Survey Center, and others. All statistics and Figures cited in this Brief are based on the PWBM microsimulation’s projections.
AB: I did not include all of the report of the Penn Wharton Budget Model microsimulation. I am using 6 of their charts and the verbiage. I looked at today’s population, the aging of it, and what would be needed to maintain a similar number of people. The population will shrink without input from other countries. We are not replacing ourselves and the population is getting older. If we need more Labor than we will need immigrants.
The numbers are there to support a conclusion and we have to decide.
Population Growth Outcomes
Figure 6 shows that immigrants’ population share is projected to increase in the future. The share of unauthorized nonresidents is projected to decline from 3.4 percent today to 2.7 percent by the 2060s.
Population growth depends on the relative strengths of factors that add people (births and immigration). This in relation to those that remove people (deaths and emigration) from the resident population. Figure 7 shows projected outcomes of births, deaths, immigration, and emigration as shares of the total population.
Panel A of the Figure 7 (about) shows births-plus-immigration will dominate deaths-plus-emigration through the next few decades. However, the strength of the former relative to the latter will weaken.
Panel B (Figure 7) shows an alternative view: Births net of deaths and net immigration. The four elements generate positive but declining population growth through midcentury.
Although U.S. birth rates have declined and are projected to remain below the population replacement rate of 2.1 per woman. Net immigration and improvements in longevity will continue to generate positive population growth through 2100.
Figure 8’s Panel A shows details of births and deaths: Deaths spiked during 2020 and 2021 due Covid-19. They are projected to revert toward 1 percent per year during the next few decades. Births, however, are projected to decline gradually over time.
Panel B of Figure 8 shows high rates of immigration during the first few years after 2020, reflecting the on-going “border crisis.” The immigration rate is projected to remain more than twice as large as the emigration rate, which helps to maintain a positive, albeit declining U.S. population growth rate.
Worker-Retiree Ratio
Figure 11: Population sizes by age group and worker-retiree ratios: ages 25-64 / ages 65+
Panel A of Figure 11 shows that the population share of persons aged 65 and older is projected to increase over time. That increase is projected to cause a rapid initial decline in the worker-retiree ratio from 2.9 today to about 2.3 by 2035, as Panel B (above-right) shows. The ratio is projected to continue declining after the 2030s and approach 2.0 by the 2060s as the population continues to grow older.
Immigration policy to restore the worker-retiree ratio over the long term
Panel A (below) of Figure 12 shows the PWBM microsimulation’s projections of annual increases among workers (aged 25-64, blue line) and retirees (aged 65 and older, red line). Both microsimulation time series include immigration into each group as projected under the current immigration policy – a quota of 675,000 per year (green line) – most of which augments the worker group.
Nevertheless, the ongoing shift of baby boomers from the worker to the retiree group implies annual increases among retirees far outstrip those of workers. Indeed, worker transitions into the older group are so large that the increase in workers (blue line) is smaller than net immigration of workers (yellow line).
The large increase in retirees relative to workers is projected to reduce the worker-to-retiree ratio (black line in Panel B (above) of Figure 12) from almost 3.0 today to 2.0 by 2075.
One potential way of preventing the decline in the worker-retiree ratio is to increase the annual immigration quota. Increases in net immigration each year would cumulatively increase the number of workers. This means that increasing the immigration quota (by some multiple of the current quota) would shift the time profile of the worker-retiree ratio upward.
How large would the quota increases have to be to restore the worker-retiree ratio, over the long term, back to its current level? The lines in Panel B of Figure 12, which show the worker-retiree ratio under alternative multiples of the current immigration quota (beginning in the year 2020) provide the answer: A quota multiple of 3.5 (uppermost dark red line) would be required.
Then there is the issue of the replacement ration which is at 1,6. 2,01 is what is needed to replace a couple. Much of the population is aging out.
This analysis was produced by Jagadeesh Gokhale. Prepared for the website by Mariko Paulson
I think that models that include increased immigration quotas should attempt to assess changes in carbon emissions. The rationale to increase immigration implicitly seems be to increase economic activity to generate “more” to have enough to distribute to an increasing population of retirees. The US economy seems tightly coupled to energy use of which something like 80% remains carbon based. Changes happen all the time, but based on trends, higher immigration almost certainly will lead to higher carbon emissions. It isn’t the only consideration, but it ought to be in these models.
Erratum.
“The data is taken” should be data are
@Dave,
Correct. But I fear we’re reaching the point where data will become both singular and plural (who says “datum” anymore?). That’s the problem with a living language–meanings evolve. I used to get annoyed when people used enormity (great evil) as a synonym for immensity (large size). Now it appears to be acceptable. Alas.
Read away: Data are” or “data is”? A pedant writes
You are off topic.
@Bill,
“You are not speaking Latin.”
Indeed. And slavishly following Latin is the root of many evils. I used to worry about split infinitives, until I learned that the reason for the prohibition was simply that infinitives can’t be split in Latin. But outside of the Vatican, who cares?
Sorry to be off-topic, but you posted the link.
The problem with increased immigration is that immigrants grow old and stop working. This isn’t a problem in places that just kick them out, but if they are immigrants, not migrant workers, any plan has to assume they’ll stay and eventually add to the retiree / worker ratio. It also has to assume that immigrants will have children possibly at a slightly higher rate than the native population but declining in the next generation.
Also, I didn’t see a chart of overall population given a higher immigration rate, but my take is that the overall population would have to grow indefinitely. That means increasing reliance on technological advances and infrastructure to support the added hundreds of millions over the next few centuries. We have stretched the Malthusian limits but we have not eliminated them.
I’ve been surprised that no one has taken a systems approach to demographics. It doesn’t seem hard to set up a transition matrix that accounts for births, deaths and immigration and compute its eigenvectors and eigenvalues. It is possible to imagine a steady state demographic, but my naive experiments with this show a higher retiree / worker ratio if it is done by simply adding to the birth rate.
One unspoken advantage of an immigration is that most immigrants are adults not children. It’s one thing to be concerned with the retiree / worker ratio, but there’s also the matter of the non-worker / worker ratio which assumes that children don’t qualify as workers until they at least approach adulthood. I know a lot of fertility boosters would love to see eight year olds slaving over puddles of molten iron, but that would make steel more expensive.
I’ve never understood the morbid dread of stagnant or falling populations. Raising the resource / population ratios is often a good thing. We saw this when the New World offered Europeans new resources and after the Black Death and Punic Wars took their demographic toll. Unrelenting population pressure discourages innovation. Maybe we can deal with a higher retiree / worker ratio by providing universal health care, improving work safety, and developing new medical technology so we can manage a lower ratio.
P.S. Consider that between 1980 and the present the per capita GDP has doubled but the value of a week’s worth of work now gets half the share of per capita GDP that it did back then. In theory, we could all have 20 hour work weeks and get the same goods and services as we did ind 1980 but have lots more time to raise children and take care of older relatives.
Kaleberg:
Maybe Soylent green? This is not the first time I have talked about population. I even chatted with Joel Garreau who wrote the article in 2006. Anddddd posted a piece at Angry Bear. To think I have been posting here for over 20 years is whatever. Thank you for your well detailed comment.