When it comes to 40-somethings, Seattle has the highest rate of fathers to kids younger than 6. Not that long ago, being an older dad would have seemed unconventional.

You know the old stereotype about men hitting midlife and rushing out to buy a sports car?

These days, in Seattle, it’s more likely to be a car seat.

Just ask George Kindl, a stay-at-home dad who lives in the Columbia City neighborhood in Seattle. Even though, at 47, he is the oldest dad at his 4-year-old daughter Alicja’s preschool, he says there are a bunch of guys right behind him in their early 40s and late 30s.

“Nobody has kids in their 20s anymore,” Kindl says.

An exaggeration, to be sure — but it’s not all that far off from reality, especially in Seattle.

Of the city’s roughly 24,000 men who have at least one child under 6, about 43 percent are 40 or older, according to my analysis of census data. That’s the highest percentage of any other major U.S. city, slightly edging out San Francisco. And it’s much higher than the national average, which is about 26 percent.

So while being an older dad like Kindl may be commonplace now, there was a time — not all that long ago — when it would have seemed quite unconventional, even in Seattle.

In 1980, just about 11 percent of Seattle dads with small kids were 40 or older — about on par with the national average. Since then, Seattle’s percentage has nearly quadrupled. Seattle women also matched the national average in 1980 — but since then, the percentage of older moms in the city has increased sixfold; Seattle now ranks third behind San Francisco and Portland.

Why have the numbers skyrocketed in Seattle?

One reason, surely, is that the trend of having children later is much more pronounced among the college-educated — folks who are more likely to put marriage and kids on hold while establishing their careers. So it’s not too surprising that Seattle — a magnet for overachievers — would be among the cities with a high concentration of older parents.

And beyond career and lifestyle considerations, it goes without saying that Seattle is now a very expensive city — even for people without kids. How many 20-somethings in this city could afford to start a family, even if they wanted to?

For George Kindl, who was 43 when his daughter was born, the timing made perfect sense. For one thing, he didn’t get married until he was 40. And even at that point, he still wasn’t sure if he was ready for the responsibility of a child — but his wife, Ewa Lichnowska, 36, convinced him that he was.

It turns out she was right, Kindl says.

“Being an older father — you have more life experience. You’re not guessing at things as much,” he explains. “You have more confidence in your parenting ability.”

Kindl feels that having a child at a mature age has made him a more patient and accepting father. “If I hadn’t waited long enough, I would have been a more reactive dad — more like my dad — than a 21st century dad.”

Kindl does admit he doesn’t always have the energy required to keep up with a preschooler — although it’s been much easier since he stopped working (he had been the assistant manager of the Harvard Exit cinema on Capitol Hill, which closed in January). His wife, a psychotherapist, is the primary breadwinner.

He does think about the prospect of being 60 when his daughter graduates high school — while that doesn’t bother him too much, it is one reason he and his wife won’t be having a second child. “I wouldn’t want to pick her up at school and the other kids being like, ‘Is that your grandpa?’ ”

If the trend continues, by then more than half the dads will be Kindl’s age anyway.