Image source: Pixabay

The Congressional Budget Office has published The Demographic Outlook: 2024 to 2054 (January 2024), which offers some recent history and projections of how the US population is evolving. Here are three snapshots:

The Role of Immigration in Total US Population Growth

The black line shows projected US population growth since 2004, with firm data up through 2020, partial data to the present, and projections up through 2020. The dark green bars show “births minus deaths”: that is, births have been outnumbering deaths, adding to overall population growth, but the gap between the two has been shrinking, and by about 2040 births are projected to equal deaths, and the drop below deaths. The light green bars show immigration. The spike in the last few years is notable. Here, as the CBO emphasizes, the future projections have a high degree of uncertainty, because they depend on policy choices. If immigration fell to zero, then on these projections, the US population would be declining in absolute numbers by about 2040.

The Aging of the US Population

Back around 1950, there were six Americans in the traditionally working-age population from 25 to 64 for every American who was 65 and older. The ratio falls over time, but when the “baby boom” generation that was born starting in 1946 started turning 65 in 2010, you can see the drop-off in the ratio become more severe for about 25 years before it more-or-less levels out again. We’re now at a ratio of 2.9 25-64-year-olds for every person over age 65, headed for a ratio of 2.2 by 2054. Many of the fundamental financial issues for Social Security and Medicare stem from this shift. But in addition, it’s also a measure of how many elderly American in the future will have many fewer children and grandchildren, and so the quantity of care and support for older American provided by family members seems sure to decline. We are shifting from a country of playgrounds and K-12 schools to a country of accessible walkways and elder-care centers.

Fertility Rates

The shifts in fertility rates (births per woman) in the last half-century are remarkable. In the decades leading up to the Great Recession from 2007-09, it looked as if fertility rates for US women were gradually rising. From 1974 up to the Great Recession, teenage fertility rates for women aged 14-29 fell slightly, but this was more than offset by rising fertility rates for the women aged 30-49. Now, these two lines are criss-crossing: that is, the number of children born to women over-30 is exceeding the number born to women under-30. This is mainly because the fertility rate for the under-30 women has fallen so sharply. Of course, this decline in births is mirrored in how the gap between births and deaths is evolving in the figure above. Again, the future predictions are subject to considerable uncertainty. The “baby boom” itself was not predicted, and fertility rates had been low in the 1930s.

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