Kay S. Hymowitz, the author of "Marriage and Caste in America," is a contributing editor at City Journal and a fellow at the Manhattan Institute. This piece is adapted from the spring issue of City Journal in the Los Angeles Times:

"...The single-mother revolution has been an economic catastrophe for women. Poverty remains relatively rare among married couples with children; the U.S. census puts only 8.8% of them in that category, up from 6.7% since the start of the Great Recession. But more than 40% of single-mother families are poor, up from 37% before the downturn. In the bottom quintile of earnings, most households are single people, many of them elderly. But of the two-fifths of bottom-quintile households that are families, 83% are headed by single mothers. The Brookings Institution's Isabel Sawhill calculates that virtually all the increase in child poverty in the United States since the 1970s would vanish if parents still married at 1970 rates.

...Experts have come to believe that these are not just selection effects — that is, they don't just reflect the fact that productive men are likelier to marry. Marriage itself, it seems, encourages male productivity. One study by Donna Ginther and Madeline Zavodny examined men who'd had shotgun marriages and thus probably hadn't been planning to tie the knot. The shotgun husbands nevertheless earned more than their single peers did.

... On the other hand, those who opt for single motherhood are hurting not just themselves but their offspring. The children of single mothers are twice as likely as children growing up with both parents to drop out of high school. Those who do graduate are less likely to go to college, even if you control for household income and the mother's education. Decades of research show that kids growing up with single mothers (again, even after you allow for the obvious variables) have lower scholastic achievement from kindergarten through high school, as well as higher rates of drug and alcohol abuse, depression, behavior problems and teen pregnancy. All these factors are likely to reduce their eventual incomes at a time when what children need is more education, more training and more planning. The rise in single motherhood was ill-adapted for the economic shifts of the late 20th century.