There are more men than women in King County, according to census data released this month. As of July 1, 2025, the county was 50.2% male and 49.8% female — roughly 8,000 more men than women, which may seem unremarkable in a county of more than 2.3 million people.

But it’s actually quite unusual, for two reasons. First, it’s a reversal after around 70 years of King County being majority female. Second, it’s exceptional among America’s largest counties: women outnumber men in more than 90% of them.

When King County was founded in 1852, it was mostly male, reflecting its roots as a remote, frontier logging and mining region that drew far more men than women. In the 1900 census, the county was 64% male. But the share of women grew steadily over the decades, and the 1950 census was the first to show the county as majority female.

That held for nearly seven decades until the 2010s, when the number of men began to grow faster than the number of women. King County flipped back to a majority male population in 2018. The new data shows the trend continuing: from 2020 to 2025, the male population grew 3.5%, compared with 3.1% for women.

Of the 100 most populous counties in the U.S., King was one of just nine that were majority male in 2025. The most male-skewed was San Francisco — a combined city-county — where men made up 50.9% of residents. King County ranked seventh.

The most female-skewed was Bronx County, one of New York City’s five boroughs, at 53.2% women.

So why do large counties typically lean female? It comes down to demographics, economics and migration.

Start with life expectancy. Women tend to live longer than men, which stacks the older age brackets in their favor — a big reason there are about 6 million more women than men in the U.S. overall. King County is no exception: Women made up 55% of residents 65 and older in 2025.

The counties that skew male typically do so by attracting working-age men through migration, often for jobs. That’s less common in large urban counties, where job markets lean toward service, administrative, healthcare and education work — fields that draw more women than men nationally. The result is a steady pipeline of women leaving rural and suburban areas for higher education and professional opportunities concentrated in big metro areas, while those same metros don’t pull in an equivalent number of men to balance it out.

The counties that skew male typically do so by attracting working-age men to industries like mining and extraction, agriculture and the military. That’s less common in large urban counties.

One male-dominated industry, though, doesn’t fit that rural mold — tech — and of course, it’s the primary reason King, San Francisco and some other large urban counties now skew male.

The tech industry’s explosive growth over the past decade in King County — anchored by giants like Amazon and Microsoft — has acted as a demographic magnet for the region. Tech remains a heavily male-dominated field, and as companies have expanded and recruited aggressively, both nationally and internationally, they’ve drawn a disproportionate number of young men here.

Indeed, the most male-skewed age group in King County was young adults, particularly those in their 30s, with men making up 52.1% and women 47.9% of that age group.

Census data reveals how male-dominated the tech field is. Of the roughly 165,000 King County workers employed in computer and mathematical occupations, 77% were men, according to the latest census figures. That single industry, more than any other factor, explains why King County’s gender demographics differ from those of nearly every other major county in the country.