Population Growth Outcomes
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.
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Key determinants of the future size and composition of the population are fertility, mortality, and net immigration rates by 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 such as age, gender, race, marital status, education, family size. region of residence, immigration, legal status, etc. using micro-data on the United States population. The data are taken 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. My goal was to look 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) relative 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 shows that births-plus-immigration will dominate deaths-plus-emigration through the next few decades but 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.
Population growth depends on the relative strengths of factors that add people (births and immigration) relative 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.
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 the Figure 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 (shown in Panel B).
While 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 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 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 that 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 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.
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AB: The assumption here is today’s worker to retiree ratio is what is desired. Everything in the graphs points to a decreasing population having gone from 2.01 to 1.6. It also shows a decreasing population of younger workers. Do we need more labor to maintain the ratio. If so, what type of Labor do we need? Degreed or high school level or? None of this has been decided. The present path is to expel all nonapproved people who have entered the US. In which case we may be shooting ourselves in the food because we would like purity of citizenship.
U.S. Demographic Projections: With and Without Immigration,” Penn Wharton Budget Model