As I have discussed in the past — both in blog items and in a February 2014 IWF policy focus — the official U.S. poverty rate, calculated by the Census Bureau, is a hopelessly flawed indicator of material deprivation and total household income. Its shortcomings include (a) a failure to account for refundable tax credits, non-cash government transfer programs, and other sources of non-money income, and (b) a failure to make proper adjustments for inflation and purchasing power. I thus agree with AEI scholar Nick Eberstadt: the official poverty rate “is a broken compass, and its misdirection has worsened steadily over time.”

Despite that, however, the Census data nevertheless tell an important story about the evolution of marriage and opportunity in modern America.

According to the figures for 2013, released on September 16, the official poverty rate among married-couple families (5.8 percent) was nearly two times lower than the rate among all families (11.2 percent), and it was more than five times lower than the rate among female-headed families with no husband present (30.6 percent). This last group — female-headed families with no husband present — accounted for 51 percent of all families living below the Census poverty line, compared with just 25 percent in 1964, when Lyndon Johnson launched his War on Poverty. Meanwhile, married-couple families went from representing 51 percent of families living below the poverty line in 1973 (the earliest year for which the Census Bureau has data on married-couple families in poverty) to representing only 38 percent in 2013.

As Brookings Institution scholars Isabel Sawhill and Ron Haskins have written: “There is not a more important divide between the middle class and the poor than the much higher share of middle-class children being raised by both parents.” Not surprisingly, a recent study by economists from Harvard and UC-Berkeley of geographic variations in intergenerational income mobility across the United States concluded that “the strongest predictors of upward mobility are measures of family structure such as the fraction of single parents in the area.”

To be sure, analysts remain divided over the exact causes of declining marriage rates — with some emphasizing primarily economic factors, and others focusing mainly on cultural trends — but it should be clear to everyone that strengthening families would go a long way toward increasing social mobility.