So much for the “great resignation” and early retirement.

Older workers flooded into the workforce last month. Buried in the latest September jobs figures published Friday is the remarkable news that pretty much all of the jobs growth during the month came from Generation X and baby boomers.

A remarkable 578,000 of people over age 45 joined the workforce in September, according to the Labor Department’s monthly household survey. Meanwhile the numbers under 45 actually fell, by 154,000.

But the biggest gains weren’t among the middle-aged, in their late 40s and early 50s.

The biggest rise, 355,000, was among the over 55s.

Even more remarkably: There has even been a big jump in employment among those aged 65 to 69.

Some 34% of Americans in that age group now have jobs—far above levels seen one or two generations ago, and just shy of the record rates seen just before the pandemic.

This isn’t a rogue reading either. So far this year employment has risen by about 1.8 million among Gen Xers and boomers, compared with barely 1 million millennials. The over 45s today make up about the same percentage of workers, 45%, as they did five years ago. The percentage of workers who are over 55 has actually edged up slightly.

Employment among those age 65 to 69 is up 11% over the past year. For the population as whole? Just 3%.

Fighting the rampant ageism in the typical American office remains an uphill battle. Older workers face discrimination on many fronts, and the Age Discrimination in Employment Act of 1967, which was supposed to make that less common, is pretty much a dead letter. Thanks to Supreme Court rulings and the rise of “enforced arbitration” in employment contracts, workers over 40 who get shunted to the basement, or shunted out the door, have few means of recourse.

But apparently they aren’t going quietly.

Maybe some employers are discovering that they would rather employ many over 45s than some of those who are younger. Who knows?

Most employment among the over 55s is among those under 70. Naturally as more people move into the second half of their senior years, into their 70s and their 80s, many of them are going to stop wanting to schlep into an office. But there’s a very good reason to hang around until you’re 70: That’s when you can claim the maximum Social Security benefit. Those who delay claiming Social Security until they are 70 will bank monthly checks that are nearly 80% bigger than those who start claiming at 62, as early as they can.

So it makes sense to keep working as long as possible, at least to 70, if you can. And apparently many are.