Welcome to middle age, millennials!

It’s hard to believe, but the oldest members of the millennial generation — typically defined as those born between 1981 and 1996 — will hit the big 4-0 this year.

Forty is often considered a milestone birthday and one that can be particularly difficult for many of us — the final nail in the coffin of our youth. And it’s been known to inspire some rather embarrassing behavior among those who try to defy their entry into middle age.

Maybe millennials will ease into their 40s gracefully. Then again, this is the generation that gave us the term “adulting” to describe those rare occasions when they have to act like responsible grown-ups. If 40 turns out to be a tough pill to swallow for millennials, it’s going to hit Seattle hard.


Because Seattle is the ultimate millennial city. Census data shows that as of 2019 (the most recent figures available), the city had roughly 270,000 millennial inhabitants — about 36% of the total population.

No other generation even comes close to matching that number in Seattle. Gen Xers, those born between 1965 and 1980, were the second largest, at just over 150,000.

To be fair, that’s partly because the millennial generation is so big. The number of births was significantly higher in the 1980s and 1990s than it was in the 1970s.


But that’s not the only reasons that Seattle’s numbers are so high. It’s largely because millennials moved here in droves throughout the 2010s. They are, in fact, the primary reason Seattle was the fastest-growing big city of the last decade.

Of course, Seattle is a very attractive place to live for young adults, with it’s thriving tech economy and easy access to gorgeous natural scenery and outdoor recreation.

In cities that didn’t attract young adults in droves, the millennial share of the population is much more modest. They make up less than 30% of the population in most large cities, and in some — including Phoenix, New Orleans and Detroit — millennials are just a quarter of the total or less.

To be sure, Seattle isn’t the only big city that was magnet for young adults in the past decade. For example, Denver nearly matches Seattle, with millennials making up 35% of its population. Boston, San Francisco and Washington, D.C. are just a little lower.

Of course, a generation is a pretty long time span — 15 years for the most recent generations — meaning that the youngest millennials are still in their mid-to-late 20s. They’re certainly not thinking about 40. The ones who probably are thinking about it, those who are 36 and older, number about 68,000 in Seattle, census data shows.

Baby boomers, the third-largest generation in Seattle, numbering about 128,000, have spent much of the past decade being blamed by millennials for just about everything that’s wrong with the world.


But millennials have a new adversary. The younger Gen Z, or zoomers, are now the “it” generation, and they seem to enjoy making fun of millennials — at least on the popular social media app Tik Tok. The point of contention, as far as I can tell, is that zoomers simply think millennials are uncool and annoying.

Gen Z is a much smaller group in Seattle than millennials, numbering about 117,000. If Seattle continues to attract young adults in the 2020s like it did in the 2010s, though, their numbers will grow rapidly. But that’s a big “if.”

Of course, Gen Z won’t be the cool, young things forever, either. The already-named Generation Alpha — those born after 2012 — are waiting in the wings. As of 2019, there were about 45,000 kids belonging to this generation, which is, of course, still being born.

The smallest generational groups in Seattle, as you’d expect, are the oldest ones: Seattleites belonging to the so-called Silent Generation and the Greatest Generation numbered only about 40,000 combined in 2019.