Our own analysis, using data from the Current Population Survey March Supplement for 2007-2012 closely parallels Pew’s findings, with some interesting nuances. In 2007, a married mother earned an average income of $57,194, nearly double that of single moms. Even after the recession hit married couples the hardest, average real incomes of single moms were just 60 percent of married moms in 2012. Differences in incomes between single and married dads also persisted over the course of the recession.

Although single dads earn more than single moms, but single parents, overall, earn less than married parents. It comes down to jobs, really. More than 80 percent of moms with spouses are employed, but only 60 percent of single mothers are in full-time jobs -- perhaps due to the difficulty of managing children alone. Similarly, single dads are less likely to be in full-time jobs (69 percent) than married dads (88 percent).

There is much more research to do, but this much we know: Single parents work less and learn less because they are the sole caretakers for their children. A recent report by the International Labor Organization shows that the US is the only country in the top fifteen most competitive ones that does not mandate paid maternity leave, paid sick leave and does not guarantee paid vacation time. New parents in the US are guaranteed their jobs for 12 weeks after the arrival of a new baby under the Family Medical Leave Act of 1993.

Paying for childcare can also be incredibly costly, driving down the incentives to work. Research confirms this intuition in several ways. Mothers who live near their mothers or mothers-in-law participate in the labor force significantly more than mothers who do not live close. Childcare subsidies can be incredibly important in allowing single mothers to find jobs with conventional or standard schedules .

The ability to work a standard schedule is more important than one might expect. A few studies have found that workers engaged in non-standard work are more likely to be assigned to routine jobs and to receive less training and fewer promotions than others. Consequently these workers earn less and are less likely to have health insurance and pension benefits than standard workers. Furthermore, nonstandard work is linked to a number of adverse outcomes for parents and children, such as work and family conflicts, marital instability, health problems for both parents and children, and poor educational outcomes for children.

Most strikingly, our data suggest that the presence or absence of children might be the single biggest factor explaining income differences between single and married mothers. For single and married women without children, the average difference in income in 2012 was $857—almost inconsequential compared to the almost $19,000 difference between single and married mothers. The differences for single and married men are also lower in the case of no children, but they are still fairly significant.

Hence the rise of single parenting, particularly single mothers, represents both a promise and a problem. If this is the path forward for society, we need to do all that we can to ensure that for these families single parenting is in fact a dream, and not the enormous challenge that it currently is today.

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Aparna Mathur is a resident scholar in studies at American Enterprise Institute. economic-policy

Hao Fu is a research assistant at American Enterprise Institute.