SSA population estimates and projections
Under-18 marriage declines and singles increase
The Social Security Administration published its 2024 Trustees Report in May. Obviously, they are interested in birth and death rates, but it hadn’t occurred to me that they also project the marriage status of the population. I was curious, so you are getting a post related to this data.
All the graphs here come from the Population page, and I’ll use the beginning of the year data. The data uses their intermediate assumption, which is found in the Trustees Report:
The intermediate (alternative II) set of assumptions represents the Trustees’ best estimate for future experience, while the low cost (alternative I) and high cost (alternative III) sets of assumptions represent more and less favorable scenarios, respectively, from the perspective of program cost and income as a percent of taxable payroll. The intermediate assumptions are also used as the point of comparison for sensitivity analysis and the central tendency for the stochastic projections presented in the OASDI annual report of the Board of Trustees (the “Trustees Report”).
It isn’t exactly clear what year we move from historical estimates to future projections. There is usually a lag in historical data of a couple of years, so I’m guessing 2022 is historical data and then it is projections, although I could be wrong, likely only by plus or minus 1 year.
One more technical note about the data. The counts here are for the Social Security area, which is defined as:
The Social Security area is composed of: (1) residents of the 50 States and the District of Columbia (adjusted for net census undercount); (2) civilian residents of Puerto Rico, the Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands; (3) Federal civilian employees and persons in the U.S. Armed Forces abroad and their dependents; (4) non-citizens living abroad who are insured for Social Security benefits; and (5) all other U.S. citizens abroad.
I’ll separate the post into three parts: overall population, under-18 marriage, and single. I don’t have a lot to say about these graphs, although I will make some points about counts vs. percentages, and I do have questions. Please leave some comments to answer my question and let me know what I should have looked at or what I missed.
Population
Figure 1 shows the population of females and males. This is in line with the U.S. Census Bureau. What is surprising is that the predictions have men overtaking the number of women by around 2075. I found this surprising, especially given the gap there has been between women and men for nearly 100 years in the graph. I don't know why this is expected, but it is worth noting.
Under 18 marriage
Figure 2 shows the number of married females ages 14–17. Yeah, it still happens, and there were about 25,000 married 14-year-old females as recently as 1975. The SSA has all of these groups dropping to 0 in a year or two. Why?
Figure 2 is a little misleading, and here we consider the data rule: Normalize properly; ask, “Per what?” If population is growing, as Figure 1 suggests, then we really should look at percentages.
Figure 3 takes Figure 2 and divides the number of married women by the number of women at that age. Figure 2 suggests that under-18 marriage didn’t start dropping until around 1975, but as a percentage of the age group, it has been dropping since 1950. I also wonder if the pre-1950 data is less accurate, as I’m surprised that these marriage rates were increasing. Figures 2 and 3 make for a good example of how two people can tell two different stories about the same data.
What about young men? Figure 4 is the companion to Figure 2 for males. The first thing to notice is the y-axis range. For example, in 1975, there were about 40,000 males aged 17 married, while for females, it was 150,000. Very different magnitudes.
The SSA still has the number dropping around 2025, but not to 0 for males. Oddly, except for age 14, the projections are to go back up from 2026 to 250. Really, we are going to see an increase in 16- and 17-year-old males marrying?
Figure 5 is the companion to Figure 3 and gives the marriages as a percentage of the population at that age for males. Here we see that the SSA is holding the marriage rates close to constant going into the future, but all but age 14 are positive. Why do they think this will be different for young men than young women?
Being single
Figure 6 shows the number of single females by age groupings. I grouped by 5-year groups, but I can’t say I have any great reason for these groupings. The SSA has the data for each age, but a graph like that would be a mess.
As you can see, each age group has seen an increase in being single or really single and never married, as the SSA has divorced and widowed categories. Again, we need to look at this as a percentage within the age group, but the dip going to 2050 is curious.
Figure 7 is more instructive and correctly normalized, yet there is still a decrease from 2025 to 2050 in all groups. What we have seen is a large increase in singles, especially for those under 30. This has been a large shift in culture over the last 50 years, and the SSA has it largely holding, despite the dips at 2050.
What about men? Figure 8 shows the counts, and we know that isn’t all that helpful. We’ll move to the percentages in Figure 9.
Figure 9 is the same pattern as Figure 7, but shifted up. 94% of men age 20–24 are single, and even the 25–29 group is at 75%. In fact, by 30-34, more than half of males are single and never married. There are people concerned about this, and personally, I would agree with their concerns, but for today, I’ll just report what the SSA has published.
A quick poll about today’s data. Please leave your thoughts in the comments.
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Please point out if you think something was expressed wrongly or misinterpreted. I'd rather know the truth and understand the world than be correct. I welcome comments and disagreement. We should all be forced to express our opinions and change our minds, but we should also know how to respectfully disagree and move on. Send me article ideas, feedback, or other thoughts at briefedbydata@substack.com.
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I am a tenured mathematics professor at Ithaca College (PhD Math: Stochastic Processes, MS Applied Statistics, MS Math, BS Math, BS Exercise Science), and I consider myself an accidental academic (opinions are my own). I'm a gardener, drummer, rower, runner, inline skater, 46er, and R user. I welcome any collaboration.