New Research on Illegal Immigration and Crime

Andrew Forrester, Michelangelo Landgrave, and I published a new working paper on illegal immigration and crime in Texas. Our paper is slated to appear as a chapter in a volume published by Oxford University Press in 2021. Like our other research on illegal immigration and crime in Texas, this working paper uses data collected by the Texas Department of Public Safety (DPS) that records and keeps the immigration statuses of those arrested and convicted of crimes in Texas. As far as we’ve been able to tell, and we’ve filed more than 50 state FOIA requests to confirm, Texas is the only state that records and keeps the immigration statuses of those entering the criminal justice system. Texas gathers this information because its runs arrestee biometric information through Department of Homeland Security (DHS) databases that identify illegal immigrants. Unlike other states, Texas DPS keeps the results of these DHS checks that then allows a more direct look at immigrant criminality by immigration status.

The results are similar to our other work on illegal immigration and crime in Texas. In 2018, the illegal immigrant criminal conviction rate was 782 per 100,000 illegal immigrants, 535 per 100,000 legal immigrants, and 1,422 per 100,000 native‐​born Americans. The illegal immigrant criminal conviction rate was 45 percent below that of native‐​born Americans in Texas. The general pattern of native‐​born Americans having the highest criminal conviction rates followed by illegal immigrants and then with legal immigrants having the lowest holds for all of other specific types of crimes such as violent crimes, property crimes, homicide, and sex crimes.

Since Texas is the only state that records and keeps the immigration statuses of those arrested, we can’t make a direct apples‐​to‐​apples comparison between Texas and other states (every state should record and keep this information so we can answer this important question). It could be that illegal immigrants in Texas are the most law‐​abiding illegal immigrant population in the country – or the least ­­law‐​abiding. Until other states start recording and keeping the data, we won’t know for sure. But there is much suggestive evidence that the illegal immigrant criminal conviction rate in Texas is comparable to their crime rates across the country.

For instance, the ratio of the nationwide estimated illegal immigrant incarceration rate to the native and legal immigrant incarceration rates is very similar to the same ratios for the criminal conviction rate in Texas. The similarity is evidence that the pattern in Texas holds nationwide, at least to the extent that convictions and incarcerations are correlated. The only way that illegal immigrants could have a higher incarceration rate is if there is something seriously wrong with our method of estimating their total population in the United States and the actual number is much smaller or we are seriously undercounting illegal immigrants who are incarcerated. Neither is very likely, but it’s important to mention the possibility.

We go a bit further in this working paper by looking at how local variation in the illegal immigrant population is correlated with crime rates on the country level in Texas for the years 2012–2018. The relationship between changes in the illegal immigrant population and crime is known as an elasticity. The elasticity between two variables estimates how one variable, the illegal immigrant population here, affects another variable like the number of illegal immigrant convictions or the total crime rate. We control for the number of law enforcement officers per capita. We basically find no relationship. The only statistically significant relationship worth reporting is a negative association between total violent crime convictions and the illegal immigrant share with a point estimate of -0.104 that is significant at the 5 percent level. This exception suggests that a 10 percent increase in the illegal immigrants share of the population is associated with a 1 percent decline in violent crime convictions in our sample of Texas counties.

Our working paper isn’t the only new research on illegal immigration and crime. Christian Gunadi, an economist who recently graduated from the University of California Riverside, examined how the DACA program affected crime rates. Gunadi tested the theory, based on Gary Becker’s crime research, that issuing work permits to young illegal immigrants increases the opportunity cost of committing crime by making it easier for them to be legally employed. Gunadi found, when he analyzed the individual‐​level incarceration data, that there was no evidence that DACA statistically significantly affected the incarceration rate of young illegal immigrants. Gunadi also looked at crime on the state level and found that the implementation of DACA is associated with a reduction in property crime rates such that an additional DACA application approved per 1,000 population is associated with a 1.6 percent decline in the overall property crime rate. That second finding is consistent with the Beckerian crime model.

Other recent research into immigration and crime similarly find no relationship between immigration and crime or a slightly negative relationship, but their methods are not as robust so I don’t place as much weight on them. However, a recent working paper written by Conor Norris and published at the Center for Growth and Opportunity used difference‐​in‐​differences and the synthetic control method to see how the passage of SB-1070 in Arizona in 2010, which was an immigration enforcement law, affected crime there relative to other states. It found that violent crime in Arizona increased by about 20 percent under both methods.

Norris’ paper is interesting and worth developing further. For instance, most of the research on the economics of crime focuses on how higher opportunity costs lowers crime rates. In that way, increasing legal employment opportunities can lower crime while making it more difficult for illegal immigrants to work can push some of them toward committing crimes because they’d have less to lose. In 2007, the Arizona state legislature passed the Legal Arizona Workers Act (LAWA) that mandated E‐​Verify on January 1, 2008. E‐​Verify is intended to prevent the hiring of illegal immigrants. Forrester and I wrote a short blog post showing that the passage of LAWA may have increased the monthly flow of non‐​citizens into Arizona state prisons, but the effect was short‐​lived as many illegal immigrants either left the state or figured out how to get around E‐​Verify.

The above new research and the vast quantity of papers on how immigration doesn’t increase crime and frequently lowers it leads to an interesting question: Why do so many people think that immigration increases crime? The Christian Science Monitor had an interview segment recently where they asked criminologists why so many Americans think immigrants increase crime even though the weight of evidence says that they are less likely to commit crimes than native‐​born Americans. According to a recent Gallup poll, 42 percent of respondents thought that immigrants increase crime, 7 percent thought that immigrants decrease crime, and 50 percent said immigrants didn’t affect crime.

Much of the effect could be that people who don’t like immigration could just ascribe all types of negative behavior to them in order to justify their dislike. This probably explains a lot of it, but it would be a disservice to stop there. We must examine the possible other reasons. Another potential reason is that many people think that immigrant criminals could have been prevented from coming in the first place, so there’s more of a focus on their crimes (availability bias) because many people think that they are more preventable than crimes committed by native‐​born Americans. In that way, many people could think that allowing any crime by immigrants is a choice and that crime could go away at the stroke of a pen. That’s not how the world works and that doesn’t explain why so many people think that crime rates go up with immigration, but if that form of control bias is combined with a conflation between the number of crimes and the crime rate then the mistake is understandable if not based on an accurate understanding of the variables.

Another reason could be that native‐​born Americans who have the same ethnicity as recent immigrants might have a much higher incarceration rate, so the respondents to these surveys lump them in together and conclude that immigrants boost the crime rate. Among native‐​born Americans, Hispanics do have a higher incarceration rate but Asians have a much lower rate. This is further complicated by the fact that Puerto Ricans, who are not immigrants, likely have the highest incarceration rate of any Hispanic sub‐​group in the United States (see Table 1) and it would be quite silly for someone to blame immigrants for the higher Puerto Rican incarceration rate.

There is more and more evidence that immigrants, regardless of legal status, are less likely to commit crimes than native‐​born Americans. However, a substantial number of Americans still think that immigration increases crime. As more evidence builds over time, we can only hope than Americans respond by updating their opinions so that they fit the facts.