Education has long been the primary pathway to social mobility in the United States. The American Dream—the idea that one’s family origin is no barrier to economic success—is plausible to the extent that we believe that our schools provide all students with equal opportunity to develop skills that will enable them to succeed in our complex society. Without such opportunity, hope for social mobility dims.

So when we ask whether America is becoming more or less equal, we should ask not only whether income and political power are becoming more unequally distributed (they are), but also whether the opportunity for social mobility is declining. We should ask whether children from all backgrounds have equal opportunities to succeed in life.

Increasingly, the answer seems to be no.

It is well known that economic inequality has been growing in the U.S. since the 1970s. Less well known, however, is the fact that inequality in educational success has also been growing. The difference in average academic skills between high and low-income students is now 30–40 percent larger than it was 30 years ago. Indeed, the difference in average test scores between high- and low-income students is now much larger than the difference between black and white students. Likewise, the college completion rate for children from high-income families has grown sharply in the last few decades, while the completion rate for students from low-income families has barely moved. [PDF]

This rising gap in academic skills and college completion has come at a time when the economy relies increasingly on well-educated workers. Largely gone are the manufacturing jobs that provided a middle-class wage but did not require a college degree. In today’s economy, young men and women without college degrees are increasingly consigned to low-wage jobs with little opportunity for advancement. So family background has become increasingly determinative of educational success, and educational success, in turn, has become increasingly determinative of economic success. The American dream has moved farther out of reach for lower-income children.

Stagnant incomes have left the children of poor and working-class families without the resources that the children of the rich enjoy.

What has caused this rise in educational inequality? Contrary to popular rhetoric, our schools are not worse than they used to be. The average nine-year-old today has math skills equivalent to those of the average eleven-year-old 30 years ago. Nor have test scores or college completion rates for students from low-income families declined; they simply haven’t risen nearly as fast as those of high-income students. Although there are striking inequalities in the quality of schools available to children from low- and high-income families, these inequalities do not appear larger than in the past. Furthermore, if schools were responsible for widening educational inequality, we would expect that test-score gap to widen as students progress through school. But this does not happen. The test-score gap between eighth-grade students from high- and low-income families is no larger than the school-readiness gap among kindergarteners. The roots of widening educational inequality appear to lie in early childhood, not in schools.

So what has been happening in early childhood? Rising neighborhood segregation by income means that low-income children are more likely to grow up in poor neighborhoods [PDF] where they have less access to high-quality child care and pre-school. High-income families, by contrast, increasingly invest more of their income [PDF] in their children. They spend more on preschool and early childhood education than they used to, more on tutors and lessons, on private school tuition, and on college. This is a reasonable response to an economy where educational success is increasingly important in securing a middle-class job. The problem, of course, is that lower-income families have not seen their income grow at the same rate as have upper-income families, and so they have not been able to increase their investment in their children. Stagnant incomes have left the poor and working-class without the resources to give their children the improved educational opportunities and supports that the children of the rich enjoy.

What can we do about this problem? The most effective way of narrowing the academic achievement gap would be to ensure that all children have access to secure, stable, and cognitively stimulating environments in early childhood, both at home and in child-care or preschool settings. And the best way to do that is ensure that we have an economy that provides families with stable incomes at a living wage. We need jobs, we need affordable health care, and we need a social safety net to support families through the hard times between jobs. We also need high-quality child-care and preschool programs for low- and middle-income children. We need programs like the Nurse-Family Partnership, in which nurses make home visits to help low-income first-time mothers develop effective parenting skills.

These do not sound like education policies, perhaps, but the best way to reduce inequality in educational outcomes is to ensure that all students start school on a more even footing. Schools alone are unlikely to remedy the very large disparities among children entering the kindergarten door. We can—and must—do more to improve our schools, of course—particularly those schools that enroll low-income students. But schools alone cannot save the American Dream.