Flickr photo courtesy of user Arileu, under a Creative Commons license.

Few institutions in America have evolved over the last 50 years quite like motherhood. More women are having their children later in life. Or they're doing so in less traditional ways: before marriage, without marriage, or with unmarried partners. Single motherhood has grown so common in America that demographers now believe half of all children will live with a single mom at some point before the age of 18.

The implications of this seismic shift in family structure are broad and deeply debated. Research suggests that children with two parents fare better in many ways — in school, in their own relationships — than children with only one at home. And those implications are unevenly distributed in society: A black child today is much more likely to be born to a single mom than a white child, or the child of a mom with a college degree.

You've likely heard these trends before, but the sweep of how dramatically they've occurred over the last half-century is breathtaking. Consider this chart, from Princeton's Sara McLanahan and Harvard's Christopher Jencks. It shows that more than 70 percent of all black children today are born to an unmarried mom, a three-fold increase in that rate since the 1960s:

McLanahan and Jencks have a helpful new paper assessing the state of children born to single moms in America, 50 years after the controversial Moynihan Report on the "the negro family" warned in 1965 that the growing number of fatherless black children in America would struggle to escape poverty.

In some ways Daniel Patrick Moynihan looks prescient. Black children today are about twice as likely as the national average to live with an unmarried mother:


McLanahan and Jencks
McLanahan and Jencks McLanahan and Jencks

And the disadvantages of education are much more severe for black children.

Research has also begun to confirm Moynihan's fears that children of unmarried moms face more obstacles in life. They're far more likely to live in poverty than children of married parents. McLanahan and Jencks have found in their research that they experience more family instability, with new partners moving in and out, and more half-siblings fathered by different men. The growing number of studies in this field also suggests that these children have more problem behaviors and more trouble finishing school. The data is less conclusive, McLanahan and Jencks caution, on how absent fathers affect a child's test scores or future earnings.

The question remains, though, of how we should respond to all of these findings — and this is where much of the controversy lies today. If children of single mothers fare worse in many ways, then married parents might make their lives better, right?

Here McLanahan and Jencks are clear: None of these findings mean that children would necessarily be better off if their biological parents married.

That's because children of unmarried moms are more likely to have a father in prison, or who's unemployed, or who sells drugs or abuses his partner. "Furthermore," McLanahan and Jencks write, "even when a child’s absent father is a model citizen, the mother often has problems that marriage cannot solve." She has less education than married moms, or she's more likely to have mental health challenges.

As a policy problem, this means that the rise of unmarried moms demands a solution far beyond marriage. So what would it look like? A key insight from McLanahan and Jencks:

Unmarried parents are not that different from married parents in their behavior. Both groups value marriage, both spend a long time searching for a suitable marriage partner, and both engage in premarital sex and cohabitation. The key difference is that one group often has children while they are searching for a suitable partner, whereas the other group more often has children only after they marry.

That implies that we should give less-educated women more reasons — like educational and career opportunity — to postpone motherhood. And we need to improve the economic prospects of those suitable partners they're searching for. These are both incredibly complicated tasks. And they point to the conclusion that the rise of single motherhood charted above is an economic story as much — if not more so — than a cultural one.