In the US, are illegal immigrants more likely to commit crimes?

Question

Trump has claimed numerous times that part of the reason we need to close the border is that the illegal immigrants are prone to crimes. I want to check these claims. Are illegal immigrants more prone to committing crimes then the average US citizen?

Obviously being an illegal immigrant is a crime itself, but for this question I want to ignore any crimes that are due to their illegal status, such as not paying taxes. I'm more interested in serious crimes, felonies and violent crimes. I'm also interested in rape as the most common accusation made by Trump. Ideally I'd prefer an answer that separately answers the question of whether illegal immigrants are more prone to rape in addition to whether they are more prone to non-rape crimes if possible.

This question refers specifically to illegal immigrants to the United States. I'll accept statistics that look at all illegal immigrants, or that look only at Hispanic illegal immigrants, since Trump often refers to Hispanic illegal Immigrants as if they are the sole form of illegal immigrant.

Answer 1

TL;DR: We don't know. Reported crimes are actually lower, but that may not reflect the real crime rate. There is no evidence that it is higher, only speculation.

Immigrant crime statistics show less crime

There have been quite a few studies on this. One review found

With few exceptions, immigrants are less crime prone than natives or have no effect on crime rates. As described below, the research is fairly one-sided.

There are some issues with the studies. For example, one type of analysis compares incarceration rates. But this isn't a good basis for comparison. The courts have an additional option with illegal immigrants that they do not have with citizens. The courts can deport illegal immigrants--even if not found guilty of a crime. So those people are never incarcerated and wouldn't show up in those statistics.

Illegal immigrants are less likely to report crimes

ThinkProgress reports

A new study released reveals that Latinos are less likely to report crimes to the police because they are afraid of being asked of their immigration status.

Why would this affect crime statistics regarding crimes committed by illegal immigrants? Because people mostly commit crimes against others like themselves. For example, the FBI's Expanded Homicide Data Table 6 shows that each grouping (white, black, Hispanic, etc.) is most likely to commit crimes against its own group. It's unclear how much this reporting discrepancy causes statistics to undercount crimes by illegal immigrants, but this would have a disproportionate impact on illegal immigrants relative to the native born. As a proxy, Hispanics report Hispanic offenders more than three times as often as non-Hispanic offenders: 439 to 123 in the statistics.

We don't have a good study of how much crime is not reported. Like with rape statistics, it is difficult to accurately estimate what is not reported. We can only point out that underreporting has a disproportionate impact on illegal immigrant statistics relative to citizen statistics.

Answer 2

No.

Numerous studies show that immigrants (legal and undocumented) are actually less likely to commit violent crime.

From The Wall Street Journal piece "The Mythical Connection Between Immigrants and Crime":

Numerous studies going back more than a century have shown that immigrants—regardless of nationality or legal status—are less likely than the native population to commit violent crimes or to be incarcerated.

A report by the American Immigration Council, published in 2015:

For more than a century, innumerable studies have confirmed two simple yet powerful truths about the relationship between immigration and crime: immigrants are less likely to commit serious crimes or be behind bars than the native-born, and high rates of immigration are associated with lower rates of violent crime and property crime.

and

A variety of different studies using different methodologies have found that immigrants are less likely than the native-born to engage in either violent or nonviolent “antisocial” behaviors; that immigrants are less likely than the native-born to be repeat offenders among “high risk” adolescents; and that immigrant youth who were students in U.S. middle and high schools in the mid-1990s and are now young adults have among the lowest delinquency rates of all young people.

and

Despite the abundance of evidence that immigration is not linked to higher crime rates, and that immigrants are less likely to be criminals than the native-born, many U.S. policymakers succumb to their fears and prejudices about what they imagine immigrants to be.

This 2015 Washington Post piece (scroll down through the article) runs up a list of sources that support the claim that there legal and illegal immigrants are less likely to commit violent crime.

Answer 3

One way to know if illegal immigrants commit more crimes would be to examine the number or people who report being victimized and see if it's higher in places where illegal immigrants are more likely to live. Or in other words, to examine whether sanctuary city policies increase the crime rate.

Researchers Daniel Martinez of U of Arizona, Ricardo Martinez-Schuldt of UNC Chapel Hill, and Guillermo Cantor of the American Immigration Council, published their summary of the current science on sanctuary cities (what they call "limited cooperation policies") and crime, which is surprisingly limited: only four studies were available as of November 2017.

The studies that were conducted contradict the scary narratives about violent cop-killing criminals and illegal immigration. The researchers write:

For the most part, it appears that jurisdictions with limited cooperation policies are either safer from crime or no different than jurisdictions without such policies (Wong, 2017; Gonzalez et al., 2017). Furthermore, limited cooperation policies may indirectly reduce crime by magnifying the crime‐reducing effects of immigration (Martínez‐Schuldt & Martínez, n.d.; Lyons et al., 2013; Ousey & Kubrin, 2017).

How can this be? They suggest that "limited cooperation policies" actually improve communication between the folks who live in the US but are undocumented and the local police force and sheriffs, an effect they call a "spiral of trust", which "strengthens formal and informal social control through community organization, thus reducing crime."

The researchers acknowledge that there is a need for better knowledge of the victims who may not report crimes. But not knowing this is no support for the political narrative that illegal immigrants make America unsafe: a citizen concerned about his or her own safety will not be affected.