Moms Increasingly Top Breadwinners, Thanks to Decline of Marriage

In 4 of 10 families, moms are the top earners, thanks to wage gains and the rise of single motherhood.

Sheryl Sandberg of Facebook delivers a keynote during the Digital Life Design conference (DLD) at HVB Forum on January 24, 2012 in Munich, Germany. (Nadine Rupp/Getty Images)

Sheryl Sandberg of Facebook delivers a keynote during the Digital Life Design conference in 2012 in Munich, Germany.

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At first, it looks like a sign of remarkable progress for women in the workplace. Women are either the sole or primary earners in more than 40 percent of all U.S. households with children under 18. That's up from just 10.8 percent in 1960, according to a new report from the Pew Research Center.

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But look a bit closer, and this shift is as much a sign of the changing American family as it is of workplace equality. The Pew analysis of Census Bureau data finds that moms aren't becoming the chief earners just because they're out-earning their husbands. It's also because husbands increasingly aren't around. Among families with children under 18, nearly two-thirds of all moms (63 percent) who are the sole or primary providers for their families are single.

Single motherhood has shown steady growth in the U.S. over recent decades. As of 2011, more than 1 in 4 mothers of children under 18 were single moms, and a recent census report showed that as of 2011, as many as 36 percent of new mothers were unmarried.

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The difference between one- and two-parent households is far greater than whether Mom wears a wedding band. Dual-earner households are far better off financially than single-parent homes, and homes where the mother is the top earner do particularly well.

"It is clear from the data that we ran that in those two parent households where you've got a married mother who out-earns their husband, those are some of the most affluent family households in the country," says Kim Parker, associate director of the Pew Social and Demographic Trends Project and a co-author of the new report.

The Pew data show that median family income for a two-parent home where the mother is the top earner is $79,800, nearly $2,000 more than for a home where the father is the top earner. Meanwhile, single-father homes earn around $35,000 a year, and single-mother homes take in only $23,000, less than one-third of their two-parent counterparts.

Of course, advances in pay equity also have played a key role in boosting some women's earnings past their husbands'. According to the National Committee on Pay Equity, full-time working women in 1960 earned only around 60 percent of what men earned. As of 2011, it was closer to 77 percent.

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While family earning patterns are changing, so are public attitudes about working moms, particularly among young adults. In an April 2013 Pew survey of more than 1,000 people, 60 percent of adults age 18 to 29 said that growing numbers of women working outside the home make it harder for parents to raise children, compared to 78 percent of adults 30 and older, according to Pew.

Likewise, 36 percent of the younger group said that women working more makes it harder for marriages to be successful, compared to 54 percent of the older adults. And though women working tends to pad a family's income, 18 percent of the 18- to 29-year-old respondents said women working more makes it harder for a family to earn enough to live comfortably, compared to 30 percent of adults 30 and older.

It may be that young adults' views will shift once they're older and therefore more likely to have spouses and kids, Parker says. But she stresses that millennials' attitudes are also signs of a social shift.

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"If you look at Generation X ... they weren't all that much different from their middle-aged and older counterparts in terms of their attitudes toward social change," Parker says. "There is something different about this generation of young adults."

While those views continue to shift, so might the way these studies of household income are conducted. More states are legalizing same-sex marriage, and the Census Bureau now tracks same-sex couples. In the future, Parker says, it's possible that these studies of two-earner households may research not whether Mom works but whether Mom and Mom or Dad and Dad both work.