Enthusiasm about the end of World War II led to one of the most famous demographic anomalies in recorded history: the baby boom. From 1946 to 1964 — admittedly a long time to be excited about the end of a war — Americans had an awful lot of babies, enough that even now the bump in the country’s population is readily visible on graphs of the population. More important, it’s visible in our culture and politics, with federal resources strained by the aging boomer population and, yet again, a baby boomer-elected president.

(An amazing bit of data that has generally gone unnoticed: George W. Bush, Donald Trump and Bill Clinton are not only all baby boomers, they were all born within a two-month window in 1946.)

The baby boom is, at this point, the only demographically significant “generation” recognized by the Census Bureau.

“The birth years and characteristics for other generations are not as distinguishable, and there are varying definitions used by the public,” the bureau’s chief demographer told me in 2015, meaning that unless you’re a boomer, your generational identity is just a bit of marketing. But that marketing can be useful, helping us to figure out how and where various age populations are alike or different.

Let’s look at the makeup of the population of the U.S. in 2015.

As we get older, there are more women than men, given that women live longer. You can see the baby boom on this chart, the big spike among those who were about to turn 70 two years ago. The definitions for “millennial” and “Generation X” are variable (as the guy from the Census Bureau noted); here’s a primer on some of the definitions. Since generations are useful mostly to sell things to people, there’s less of a fight over generations that preceded the boomers, so we’ll use Pew Research’s definitions. (Note that kids born today aren’t millennials — they’re members of an as-yet-unnamed generation that’s already the subject of marketing push and pulls.)

What’s remarkable about this graph is that there are still 3.7 million members of the greatest generation sticking around — the group that did the fighting in World War II and the procreating shortly thereafter. (A bunch of millennials think that they are the greatest generation; they are incorrect.)

It raises the question: For how long will each of these generations stick around?

The Census Bureau offers projections for the composition of the population in the future. By 2055, for example, it figures that there will still be 30 million people in the United States who were born before 1965 — most of whom will be boomers. (By official definition, the baby boom ended in 1964.) How many of those people are members of the greatest or silent generations (the group between greatest and boomers) is hard to say.

To answer the question, then, we can look at another bit of data. There exists a never-ending contest for the title of “Oldest Person in the World,” which FiveThirtyEight’s David Goldenberg tracked a few years ago. The age at death of the oldest person in the world keeps ticking upward alongside life expectancies; as I write, the oldest person in the world is a 117-year-old Italian woman. Before the 1990s, none of the previous oldest people had lived that long.

We can use the pattern of the ages of those people to project the long-term trend. That is, if the oldest people in the world keep living longer, how old will the oldest person in the world be in future years? Put visually:

(This is the world, not just the United States, but we’ll let that slide for the sake of our argument.)

Now it becomes fairly simple to compare those maximum ages with the maximum ages each year of members of each generation.

Here’s how it works. The tail end of the greatest generation is in 1927. By 2046, the oldest person from 1927 will be 119 — the same age we can project the oldest person in the world to be. The next year, that last member of the greatest generation will be older than the projected oldest person in the world, and therefore no longer alive. There is flexibility in both directions; the oldest-ever person in the world, Jeanne Calment, hit 122 years, so the greatest generation could hang on a bit longer. Or, the last member of the generation could fail to hit the projected mark, and leave us that much sooner. (Belated apologies for how macabre this whole thing is.)

The last member of the silent generation will likely have left us by 2067. The last boomer, by 2088. The last Gen Xer, by 2108, and the last millennial by 2132 — assuming the most generous definitions of those generations.

To circle back to the beginning, that means that we could have 17 more baby boomer presidents, if each serves one term.

We could elect 18 — but the one elected in 2088 at the age of 124 likely wouldn’t live to see his or her inauguration.