Poverty and inequality in America are hot topics these days, and not just among the Occupy Wall Street crowd. Yet amid all the chatter, hardly anyone talks about the greatest driver of poverty: the rapidly rising number of babies born to unmarried mothers.

Today, over 40 percent of U.S. births – four in 10 – occur outside marriage. In 1960, it was below one in 10. The trend isn’t limited to just a few states, either.

All states, including Arkansas, have seen similar trends, as illustrated by a new Heritage Foundation report based on data from the U.S. Census Bureau. Sadly, in Arkansas the number of children born to single mothers – nearly 46 percent – is higher than the national average.

Couple this trend with the finding that children born outside marriage are roughly five times as likely to be poor as those born to married parents, and we have a recipe for economic disaster.

Although births to unwed mothers often are attributed to teens, less than 10 percent of all unwed births in America overall, as well as in Arkansas, are to women under 18. Roughly 80 percent of out-of-wedlock births are to women between 18 and 29, and most often their formal education went no further than a high school diploma.

Rather than a teen issue, then, the rise in childbearing outside marriage springs from a breakdown of relationships among young adult men and women in low-income communities.

Yet, it isn’t because these men and women don’t value marriage. In fact, just the opposite is true. Marriage is valued so highly in low-income populations that it has become a crowning event – a ceremony symbolizing arrival into the middle class – rather than a crucial pathway leading to the attainment of middle-class status. Having children – also extremely valued – occurs on the pathway to marriage, not afterward.

Unlike their college-educated counterparts who wait until after marriage to have children, these young adults are doing the exact opposite. Poverty, a string of unstable relationships and huge welfare costs to the taxpayer are the results.

This difference in marriage and childbearing patterns between low-income young adults and their educated peers has led to a society that is steadily splitting into a two-caste system – with marriage and education as the dividing line. In the higher-income third of the population, children are raised by college-educated, married parents; in the lower-income third, children are raised by single parents with no more than a high school education.

Indeed, marriage decreases poverty at all education levels. The effectiveness of marriage in preventing poverty is the equivalent of adding five to six years to a parent’s education, the data indicate. Beyond the economic effects, of course, marriage has a wide variety of other benefits for adults and children.

Unfortunately, we rarely teach the importance of marriage to young men and women in low-income communities. For decades now, the schools, the welfare and health care system, public authorities, and the media have refused to address this subject. They have failed so much as to tell youth that having a child outside marriage is not a good idea.

Liberals, who attribute unwed childbearing to lack of access to birth control, have attempted to address the problem by pedaling contraception. Yet research shows that low-income women who become pregnant outside marriage (whether as minors or adults) report that they almost never got that way because they lacked knowledge about, or access to, birth control.

These women say they highly value motherhood. They report that their births generally weren’t unintentional – or at least not completely so.

Promisingly, a few states, Georgia and Kansas among them, are taking action to stem the breakdown of marriage and the increase in unwed births. Arkansas and the rest of the states can take similar steps.

A good place to start: simply telling boys and girls that it’s important to wait to have a baby until after marriage. This could involve a public service campaign using billboards and online ads, or making sure Title X clinics offer educational pamphlets on the benefits of marriage.

The options are many. And the promise of the American Dream depends on strong marriages.

Kay Hymowitz, author of “Marriage and Caste in America: Separate and Unequal Families in a Post-Marital Age,” noted in a 2007 lecture at The Heritage Foundation that “erasing the bond between marriage and child rearing leads to a weakening of our country's ability to carry out…its promise of fairness, equality, opportunity and prosperity.”

Hymowitz added: “Instead, the result is separate and unequal families as far as the eye can see.”

It’s long since time for Arkansas, and every other state in the union, to address the growing inequality created by the rapid rise in childbearing outside marriage.

Robert Rector, senior research fellow in domestic policy at The Heritage Foundation, and Rachel Sheffield, research assistant, are co-authors of the paper “Understanding Poverty in the United States: Surprising Facts About America's Poor.”