The Economist reports that "Traditional marriage has evolved from a near-universal rite to a luxury for the educated and affluent."

Americans with a high-school degree or less (who account for 58% of the population) tell researchers they would like to marry, but do not believe they can afford it. Instead, they raise children out of wedlock. Only 6% of children born to college-educated mothers were born outside marriage, according to the National Marriage Project. That compares with 44% of babies born to mothers whose education ended with high school.

“Less marriage means less income and more poverty,” reckons Isabel Sawhill, a senior fellow at the Brookings Institution. She and other researchers have linked as much as half of the income inequality in America to changes in family composition: single-parent families (mostly those with a high-school degree or less) are getting poorer while married couples (with educations and dual incomes) are increasingly well-off. “This is a striking gap that is not well understood by the public,” she says.

Do not expect the Democratic Party, however, to make an issue of the marriage gap in next year’s elections. Unmarried women voted overwhelmingly for Barack Obama. “You don’t want to suggest to someone who isn’t married and has children that they should be married,” says Ms Sawhill. “That is a denigration of their lifestyle.”