ACCORDING TO THE DEPARTMENT of Homeland Security, more than 11 million undocumented immigrants currently reside in the United States. Very little is known about where and how much they work. A recent study conducted by George Borjas, the Robert W. Scrivner Professor of Economics and Social Policy, made some important and surprising discoveries. Here Borjas talks to HKS Magazine about what he found.

Q: What made you decide to take on this study?

We have all these debates about granting amnesty or changing the status of 11 million people. We’re talking about a big policy shift without any sense of what’s going to happen as a result. My interest was just to try to provide a little more information about how to think about this long-term. You often hear that illegal immigrants or undocumented immigrants come to the United States to work. I wanted to see if that was true.

Q: And what did you find?

I found that undocumented men work at much higher rates than legal immigrants and native workers, and if you look at it over time, you see the gap is growing very, very rapidly. Ten to 15 years ago the gap in employment between undocumented and native workers was there, but it wasn’t so large. Now it’s there and it’s very, very large. Additionally, when you see a wage change, undocumented people keep working no matter what—whether the wage is lower or higher. That’s not true for natives.

Q: What was your most striking discovery?

When I looked to see what happens when wages change was really remarkable. Undocumented immigrants basically work more or less full-time, and that’s that. The study found a really strong permanence to their work status. It isn’t affected very much by the wage going up or down.

Q: What has been the reaction to the findings?

The reaction to the paper surprised me. What’s surprising is the diversity of ideological perspectives taking on this paper and interpreting it in their own way. Some people say this shows that undocumented immigrants are hard workers; other people say they work so hard that it affects other people who want to work. My paper says nothing whatsoever about that. It just says that undocumented persons work, and they work a lot, and they’re not responsive to wage changes. I have not gotten involved in any of these ideology-driven discussions. Let them say whatever they want to say.