America has gotten older since 2010 — which is a bigger deal than it sounds

Let’s start with Box A. (These boxes mostly highlight the data for women, but the same effects are seen for men as well.) You’ll notice that at this point the thin columns, representing 2010, extend well above the thicker columns. That means that there were more young people (ages 0 to 5 or so) in 2010 than there are now. In other words, the United States was doing a better job of repopulating itself, having more kids a decade ago than last year. Last year was anomalous, of course, given the pandemic, but the number of 1-year-olds last year was also lower than the number of 1-year-olds in 2010.