Sen. Bernie Sanders (I-Vt.) spent much of his presidential campaign calling for a political revolution that would take money out of politics and reduce income inequality. His policy proposals, such as single payer health insurance and higher taxes on the rich, were directly aimed at accomplishing those goals.

But new evidence shows that one of Sanders’ favorite ideas—free college—would not reduce income inequality. In fact, it might make it worse.

The research, which is set to be published later this year, was highlighted in an UpJohn Institute research brief a few weeks ago, around the time that Hillary Clinton partially endorsed Sanders’ college plan. The authors find that college graduates earn more than those without a college degree—a finding on which experts nearly universally agree.

But they also found that the magnitude of this college wage premium isn’t felt equally: It’s larger for people who grew up in non-poor households than it is for those who grew up in poor households. Although college does lift people up, the poor reap smaller benefits than the well-off do. So if a poor family and a middle-class family both send kids to college, the economic gap between them may actually grow.

College, it turns out, is not the great equalizer.

These findings, first introduced on a Brookings Institution blog post in February, pose a challenge for policymakers across the political spectrum who see education as the key to reducing inequality. “Simply increasing everyone’s college education is not going to reduce most measures of inequality,” said Brad Hershbein, an economist at UpJohn who was a co-author of the study.

Hershbein and his co-author, UpJohn senior economist Timothy Bartik, use data on specific individuals and their descendants going back until 1968, allowing them to track their career earnings profiles by education and family background. They define low-income families those with an income below 185 percent of the federal poverty line—about $45,000 for two parents and two kids.

The results: For people who grew up in families with income below 185 percent of the poverty line, the college wage premium—the additional lifetime earnings from a college degree—is 71 percent. For those earning above that threshold, the premium is much larger—136 percent. As the authors write, “The average college graduate from a low-income family earns as much at career peak as the average college graduate from a higher-income family at career beginning.”

Hershbein and Bartik also broke down the data into different demographic groups to examine which subgroups have the largest disparities. They discovered that for those with median earnings, the college wage premium was larger for those from poor families than from middle class or rich ones. In other words, a college education does provide greater access for people who grew up poor to the middle class.

But as you move up the income distribution, that pattern reverses. For college graduates at the 75th or 90th percentile, the gap in the college wage premium widens significantly. “It’s the people who are breaking into not just the top 1 percent but the top quarter and beyond that are driving the gap,” said Hershbein.

Another way to think about this: The authors also found that if you drop the top percentile of wage earners from the analysis—just looking at the bottom 99 percent of the income distribution— the difference in the college wage premium between people from non-poor backgrounds and people from poor backgrounds nearly disappears. College graduates from poor families simply have very little access to the very top of the income distribution.

Focusing the analysis just on whites or men has the opposite effect: the gap is much larger. This makes intuitive sense, since the top 1 percent is largely made up of white men. Accordingly, there is almost no gap in the college wage premium for women or African-Americans from different socioeconomic backgrounds. That’s not necessarily good though, since it comes from the fact that women and African-Americans—no matter their background—struggle to make the top 1 percent.

“There are some [whites and men] who make several hundred thousand dollars, several million dollars,” said Hershbein. “If you look at the same thing for African-Americans or women, there are far fewer people making that much money.”

Hershbein and Bartik plan to further dive into the data more in the months ahead to determine why this gap exists, but they have a few theories, including that network effects, which are typically stronger for people from middle class or high-income families, play a larger role in life outcomes than previously imagined. A college degree is not enough for people from low-income families to make up for that advantage in connections. Further exacerbating this trend could be that people from middle class or high-income families often go to elite universities that offer access to high-paying careers, which may be unavailable for college grads from less prestigious schools.

None of this means that the individual decision to go to college is a bad idea. On the contrary, the college wage premium is significant, even for people from low-income households. But it does mean that college isn’t the solution to rising inequality.

That finding doesn’t just push back on Sanders’ free college plan. It pushes back on much of the public policy world which has held for years, on the right, left and center, that education is a key to reducing income inequality. Sanders also offered other policies, including higher taxes on the rich, that would accomplish that goal. A modest increase in the minimum wage, as just about all Democrats support, is likely to moderately reduce inequality as well.

Authors: