For just the second time in history, women outnumbered men as the majority of the U.S. paid workforce, buoyed by fast job growth in health care and education over the last year, as well as the ongoing tight-labor market.

At first glance, the shift is tiny and easy to miss: Women worked 50.04% of payroll jobs in December, up from 49.99% the prior month. But the figure reflects a larger, ongoing trend. Of the 145,000 jobs picked up in December throughout the economy, women won most of them — 139,000, according to Labor Department data.

"Why is today a milestone? It's a milestone because it's really heralding the future and not just telling us where we are today," said Betsey Stevenson, a professor of public policy and economics at the University of Michigan and an Obama administration economic adviser.

Indeed, women’s share of the workforce has been growing steadily for the last few years. Zooming out, looking at all workers, including farm workers and those self-employed, men still outnumber women. But women have been joining the workforce at a faster pace than men since 2018. Economists say this narrowing in the gender gap comes as women have been getting college degrees in larger numbers than men, which has radiated out to the job market as they reach higher ranks in the office.