The Outliers

The population bump has reached the right-hand end of the curve: “The aging of baby boomers, those born between 1946 and 1964, who were ages 57 to 75 in 2021, is partly driving the growth in the adult population.”

The Census also notes, “[t]he slow decline of the younger population is in part due to a general decrease in fertility, ongoing since 2007,” though the CDC data they link to shows the flattening, after the unusual spike of the Baby Boom, of a trend from the beginning of the century. This is not a general decrease in fertility since 2007 but a century-long decline obscured by the fact that the Baby Boom generation is a HUGE outlier. That demographic wave has to die out before we can easily separate anything from its effects. Am I completely missing something from this chart that leads me to see something completely different from the written analysis? Or are statisticians so divorced from the specifics that they can’t see the relatively obvious?

Hamilton BE, Lu L, Chong Y, et al. Natality trends in the United States, 1909–2018. National Center for Health Statistics. 2020.

The fertility rate trend has been in decline for the entire period covered by this chart. The increase in births between 1913 and 1914 brought the rate back to the 1909 starting point, but it began sliding immediately, returning to form in 1921 after the sharp dip correlated with the Spanish Flu and American participation in World War One, then falling off a cliff as the Lost Generation partied through the Roaring Twenties before hitting the floor in 1933.

Why a Baby Boom? It wasn’t the end of WW2. As we can see in the graph, the upward curve begins in 1937, well before 1945. There are distinct drops from 1943-1945, during WWII, from 1948-1950, Korea, and 1963-1968, Vietnam, an uptick between 1968 and 1970, then a sharp drop until Watergate in 1973–just coincidentally 50 years from the nadir of the previous decline.

It seems more likely that it was multiple generations having children at the same time, even some of the Lost. And we can easily see in the chart below that everyone between 15 and 44 was making like rabbits. But is the notion that the Baby Boom was in response to horny boys home from the war and the general prosperity after World War Two incorrect or merely oversimplified? If the dataset were longer, we might be able to tell. The boom’s apex, in 1957, was still lower than the rate in 1916. Take away the boom, and the curve looks like the flattened end of a long slide. Perhaps the better question is why that long slide?

Why was the Lost Generation so lost?

My grandparents of the Greatest Generation didn’t go away to war: they married and had children; my parents were of the tail end of the Silent Generation. I’m of Generation X, my children of Generation Z. And while those labels are possibly useful marketing categories and perhaps even predictors of electoral behavior, they aren’t much use in helping us to understand.


  1. I wonder how widespread this fertility pattern is. A lot of my usual reading tends to think that ideas and politics alone are what shape the patterns in the world, as if those can be isolated from the weather, food, and health. For instance, from the mid-to-late 1980s there was a panic about teen pregnancy rates which was blamed on moral ills, but births over all age groups were rising during that period, until falling coincident with the 1990 recession. Children, like trees, are a hope for the future.

    There’s some speculation that the 1889-1892 pandemic may have been caused by a coronavirus rather than influenza. Child survivors of this pandemic were members of the Lost Generation.

    Brüssow, Harald; Brüssow, Lutz. “Clinical evidence that the pandemic from 1889 to 1891 commonly called the Russian flu might have been an earlier coronavirus pandemic”. Microbial Biotechnology. doi:10.1111/1751-7915.13889. ISSN 1751-7915.

    Mark Honigsbaum; Lakshmi Krishnan. “Taking pandemic sequelae seriously: from the Russian influenza to COVID-19 long-haulers.” The Lancet. October 12, 2020. Vol. 396, Issue 10260, pp. 1389-1391. doi:

    1. Technical advancements in the manufacture of condoms in 1912 and 1920, and the increased usage, as indicated by sales data, may have had a contributing effect.

      Collier, Aine. The Humble Little Condom: A History. (Amherst, NY: Prometheus Books, 2007)

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