A high fraction of immigrants are young, low-skilled, Hispanic males. Given these demographics, I long assumed that immigrants would have relatively high crime rates. While I kept this problem in perspective, I took it for granted that increased crime was a genuine drawback of immigration.

I was wrong.

A fascinating NBER Working Paper (earlier, free version here) by Kristin Butcher and Anne Piehl shows that, despite their demographics, immigrants are drastically less criminal than native-born Americans. In fact, immigrants have one-fifth the incarceration rate of natives. Yes, natives are incarcerated at five times the rate of the foreign-born:

Using the 1980, 1990, and 2000 Censuses, we show that 18-40 year-old male immigrants have lower institutionalization rates than the native born in each year. The gap in these institutionalization rates widens over the decades, and by 2000 immigrants have institutionalization rates that are one-fifth of the native born.

Is this base statistical trickery? Not likely; these are raw numbers that anyone can double-check against the census. Could these results simply reflect the practice of deporting criminal aliens? Nope; our actual practice is to make immigrants serve their full sentence before expelling them.

But how can we reconcile the facts with the demographics? Butcher and Piehl show that given their demographics, we should expect immigrants to commit crimes at double the native rate. But for some reason(s), demographics yield a massive overprediction; immigrants commit crimes at one-tenth the expected rate given their demographics. Yes, if immigrants acted like otherwise similar natives, they were be ten times as criminal as they actually are.

Why would this be so? The main theories that Butcher and Piehl explore: (1) Immigrants self-select for law-abiding behavior; (2) Immigrants are more responsive to deterrence than natives. Personally, the most plausible story to me is that immigrants feel lucky to be in the U.S. and don’t want to forfeit their “big break,” so they try extra-hard to stay out of trouble.

In any case, given my repeated attacks on anti-foreign bias, I should have been more skeptical of popular claims about immigrants’ criminal propensities. So to every immigrant out there, I’m sorry. I’ll try not to let it happen again.

P.S. I won’t be posting much during the next two weeks. Why? Well, let’s just say that if you see me at Comic-Con, don’t hesitate to say hi!