HAT WOULD A SOCIETY in which women are on top look like? We already have an inkling. This is the first time that the cohort of Americans ages 30 to 44 has more college-educated women than college-educated men, and the effects are upsetting the traditional Cleaver-family dynamics. In 1970, women contributed 2 to 6 percent of the family income. Now the typical working wife brings home 42.2 percent, and four in 10 mothers—many of them single mothers—are the primary breadwinners in their families. The whole question of whether mothers should work is moot, argues Heather Boushey of the Center for American Progress, “because they just do. This idealized family—he works, she stays home—hardly exists anymore.”

The terms of marriage have changed radically since 1970. Typically, women’s income has been the main factor in determining whether a family moves up the class ladder or stays stagnant. And increasing numbers of women—unable to find men with a similar income and education—are forgoing marriage altogether. In 1970, 84 percent of women ages 30 to 44 were married; now 60 percent are. In 2007, among American women without a high-school diploma, 43 percent were married. And yet, for all the hand-wringing over the lonely spinster, the real loser in society—the only one to have made just slight financial gains since the 1970s—is the single man, whether poor or rich, college-educated or not. Hens rejoice; it’s the bachelor party that’s over.

The sociologist Kathryn Edin spent five years talking with low-income mothers in the inner suburbs of Philadelphia. Many of these neighborhoods, she found, had turned into matriarchies, with women making all the decisions and dictating what the men should and should not do. “I think something feminists have missed,” Edin told me, “is how much power women have” when they’re not bound by marriage. The women, she explained, “make every important decision”—whether to have a baby, how to raise it, where to live. “It’s definitely ‘my way or the highway,’” she said. “Thirty years ago, cultural norms were such that the fathers might have said, ‘Great, catch me if you can.’ Now they are desperate to father, but they are pessimistic about whether they can meet her expectations.” The women don’t want them as husbands, and they have no steady income to provide. So what do they have?

“Nothing,” Edin says. “They have nothing. The men were just annihilated in the recession of the ’90s, and things never got better. Now it’s just awful.”

The situation today is not, as Edin likes to say, a “feminist nirvana.” The phenomenon of children being born to unmarried parents “has spread to barrios and trailer parks and rural areas and small towns,” Edin says, and it is creeping up the class ladder. After staying steady for a while, the portion of American children born to unmarried parents jumped to 40 percent in the past few years. Many of their mothers are struggling financially; the most successful are working and going to school and hustling to feed the children, and then falling asleep in the elevator of the community college.

Still, they are in charge. “The family changes over the past four decades have been bad for men and bad for kids, but it’s not clear they are bad for women,” says W. Bradford Wilcox, the head of the University of Virginia’s National Marriage Project.