President Barack Obama has made reducing economic inequality a central goal of his last term in office. A good start would be to maintain and expand efforts to ensure children aren’t at a disadvantage before they even get to grade school.

In his State of the Union address, Obama laid out his vision of an America “where prosperity is widely shared and opportunity for all lets us go as far as our dreams and toil will take us.” In her response, Representative Cathy McMorris Rodgers emphasized the widely held view that income disparities might not be a problem if everyone has an equal shot at ending up in the top 1 percent. Horatio Alger’s story of the poor boy who succeeds through a combination of pluck and personal merit remains deeply ingrained in American culture. Commentators as far back as Alexis de Tocqueville were struck by the New World’s radical equality of opportunity.

Yet as economic mobility has increased in Europe and Canada, it has stagnated in the U.S. A recent study of millions of anonymous U.S. income tax records shows that among children born to families in the bottom fifth of the income distribution, the chances of rising to the top fifth have held steady at less than 10 percent since 1971. By this measure, people in Scandinavia are now about twice as likely to go from poor to rich.

Does this relative lack of mobility mean that social programs introduced in the 1960s as part of the “War on Poverty” have failed, as people such as Congressman Paul Ryan have argued? Not at all. Although the rungs on the ladder of prosperity are spaced further apart, making it harder to climb, the condition of both rich and poor children has measurably improved.

One of the primary motivations for the creation of food stamps and the Women, Infants and Children program was the appalling level of malnutrition among poor children in the early 1960s, especially in the South. Diseases such as scurvy and rickets, prevalent back then, are now virtually unheard of in the U.S. Infant mortality has fallen to 6.05 deaths per 1,000 in 2011 from 26 deaths per 1,000 births in 1960, an achievement that can also be attributed in part to better public health insurance coverage of pregnant women through Medicaid, and to some states’ introduction of nurse home visits for first-time parents.

Following Ronald Reagan’s lead, pundits on the right often point out that the official poverty rate has flatlined over the past several decades. This is largely because the official measure does not count benefits such as food stamps, Medicaid, public housing or the earned income tax credit, all of which have greatly improved life for the poor. A recent Council of Economic Advisors report showed that if these programs were included, the share of families with incomes below today’s poverty threshold would have been 16 percent in 2012, down from 26 percent in 1967. Data on families’ consumption, rather than income, tell a similar story of improvement.

Understanding what works and what doesn’t, and how much worse things would be without the War on Poverty, is crucial now that programs to help poor children face potentially severe cuts. There will, for example, be a battle when the Women, Infants and Children program comes up for reauthorization in 2015. States facing their own budget difficulties will give programs such as nurse home visits a hard look.

Sometimes the evidence is more nuanced than can be conveyed amid the shouting of public debates. For example, research strongly suggests that high-quality preschool programs lead to better outcomes for disadvantaged children. Hence, one goal should be to improve the often poor quality of child care that is available to poor and middle-class families. Creating a universal pre-kindergarten program -- a proposal Obama repeated in his address -- would be one solution. There may be others.

Until recently, politicians from both parties agreed that every American child deserved a level playing field. Perfect equality of opportunity might be an unattainable, but that is no reason to abandon the goal.

We’ve done a good job protecting our youngest from the full impact of the economic dislocations facing American families. We need to maintain the gains we’ve made and focus on improving protections for all our children as they grow. To that end, let’s set partisan bickering aside, pay attention to what research tells us and act on it.

(Janet Currie is the Henry Putnam Professor of Economics and Public Affairs at Princeton University and the director of Princeton’s Center for Health and Well Being. She also directs the Program on Families and Children at the National Bureau of Economic Research.)

To contact the writer of this article: Janet Currie at jcurrie@princeton.edu.

To contact the editor responsible for this article: Mark Whitehouse at mwhitehouse1@bloomberg.net.