In 2016, female voters under 30 years old voted for Hillary Clinton over Donald Trump 63 percent to 31 percent. Males in the same age cohort gave Clinton a much smaller edge, voting for her 46 percent to 42 percent. That’s a 17-point gender gap.

Since the election, the gap in leanings has gotten even bigger, as white male millennials have shifted to the G.O.P. A recent Pew survey of midterm party preference suggests that women under 35 tilt Democratic by an astounding 68 percent to 24 Republican. Men under 35 now tilt Republican 50 percent to 47 percent Democratic.

As Ed Kilgore pointed out in New York magazine, that’s a 21-point gender gap in Democratic support and a 26-point gender gap in Republican support. More than ever, millennials are staggeringly divided by gender, while older generations show far smaller differences.

What is going on here?

Perhaps two interrelated stories:

Female mobilization. If you look at the research, you find that millennials are not so divided on gender roles. Both sexes increasingly favor a feminist attitude in the workplace and a neotraditionalist attitude at home. They want both sexes to have equal opportunities at work, but year by year more young people believe that the best home is the one where the man is the outside “achiever” and the working woman is the primary caregiver. In 1994, for example, 42 percent of high school seniors believed this; by 2014, 58 percent did.

Trump and the #MeToo movement have brought the workplace side of that consensus to the top of mind, at least among young women. According to an MTV-Public Religion Research Institute survey, 63 percent of women ages 15 to 24 say there is a lot of discrimination against women at work, while only 43 percent of young men say that.