Last week, new data from the U.S. Census Bureau revealed that the U.S. just saw the largest annual increase in poverty recorded in our nation’s history: In 2009, 3.7 million more Americans joined the ranks of the poor.

The recession bears part of the blame, but media outlets have failed to inform the public about the long-term root cause of poverty in this country: unwed childbearing. Buried in the Census report are startling figures revealing that the collapse of marriage is creating this crisis of poverty. Single-mother families are almost five times more likely to be poor than are married couples with children; overall, nearly 70 percent of poor families with children are headed by single parents.

The biggest secret in the Census report: Marriage is America’s number-one weapon against child poverty. Tragically, however, marriage has been rapidly declining in our society and the number of women who have children outside of marriage has soared. Historically, unwed childbearing was rare. In 1964, when the federal government launched its War on Poverty, 6.8 percent of births were to single mothers. Today, the unwed birthrate has climbed to 40 percent: four of every ten births are to single mothers. For Hispanics and African Americans, the rates rise to nearly 50 and over 70 percent.

While the media is quick to decry the crisis of teen pregnancy, the fact is that less than 8 percent of new single mothers are minors. In fact, the overwhelming majority of unwed births are to young adult women in their 20s. And because most of these women have little education, they are unable to provide for themselves and their children and, consequently, a large portion of them end up on welfare.

However, if these women were to marry the fathers of their children, nearly two-thirds of them would be immediately lifted from poverty. Contrary to conventional wisdom, nearly all unwed fathers are employed and earn enough money to move their families out of poverty. But, tragically, few unwed parents marry.

It’s not a question of money: The government has continued to pour funds into welfare programs over the past several decades, to the point that the United States will soon be spending $1 trillion a year on programs for the poor. Yet poverty rates have significantly climbed.

And while data clearly show the importance of marriage to reducing poverty — not to mention its association with numerous other positive outcomes for children — the federal government has done relatively little to promote it. In fact, the Obama administration has sought to undo efforts put into place during the previous administration aimed at helping low-income couples build strong marriages.

If Americans are serious about reducing poverty and getting control of federal welfare spending, it is vital to strengthen the institution of marriage. There are two steps that the United States can take to help low-income couples build healthy marriages, and by so doing, break the cycle of poverty. First, the federal government must reduce the marriage penalties in current welfare programs. Second, government and society should send a clear message to young people in low-income communities that having a child outside of marriage dramatically increases the odds of long-term poverty and other ills. Just as we tell young people that dropping out before you finish high school is likely to harm your future, we should forcefully inform low-income youth that having a child outside of marriage is self-destructive. It’s the surest road to long-term poverty.

The current growth of the welfare state is unsustainable. Over the next decade, government will spend more than $10 trillion on cash, food, housing, and medical care for the poor. It will be very difficult to slow the growth of welfare spending if marriage continues to disappear in the bottom half of the population.

Unfortunately, both government and popular culture treat marriage as an outmoded, irrelevant institution. To reduce poverty and limit the growth of the welfare state, that attitude must change.

— Robert Rector is a senior research fellow at the Heritage Foundation.