Do Immigrants Threaten US Public Safety?

1. Introduction

The relationship between immigration and crime is a hot topic right now, but it is not a new one. During the peak of US immigration in the late 19th and early 20th centuries, there was a perception that the two activities were related (Moehling and Piehl 2009, 2014). In fact, a common claim in congressional debates was that foreign countries actively encouraged convicts to emigrate to the US (Moehling and Piehl 2007). Immigration was also sometimes seen as underlying the rise of certain criminal institutions in the US, such as the mafia. The characterization of the US-Mexico border as a lawless place rife with crime and illicit activity dates back more than a hundred years, as does the debate over whether immigration exacerbates crime and other social ills (Moehling and Piehl 2009, 2014).¹For example, in 1911, the US Immigration Commission, also called the Dillingham Commission, concluded that federal regulation was not effectively excluding criminal aliens and proposed strengthening restrictions on immigration.

Charges that immigrants, particularly unauthorized ones, endanger public safety have resurfaced in recent years and played a central role in the 2016 presidential election and in the government shutdown of early 2019. Immigration policies, most notably President Donald Trump’s call to “build the wall,” are being proposed and, in some cases, implemented partly on the basis of claims that immigrants are responsible for a disproportionate share of crimes and that devoting more resources to immigration enforcement would reduce illegal immigration and crime. Increased border and interior enforcement, crackdowns on sanctuary cities, and the reinstatement of Secure Communities are examples of policies proposed or implemented in the name of decreasing illegal immigration and bolstering public safety.

Such claims are contrary to the large body of research that shows that immigrants are less likely than US natives to commit crimes and that areas with more immigrants—including unauthorized ones—tend to have lower crime rates than areas with fewer immigrants. Further, there is little credible evidence that unauthorized immigrants are more likely to commit crimes than US natives. While there is a growing consensus that the massive increase in border enforcement over the last two decades has reduced the inflow of unauthorized immigrants, there is no clear evidence that it has led to a drop in crime rates. Research suggests that the relationship between immigration enforcement, either along the border or in the interior, and crime rates is complicated. Tougher immigration enforcement can even lead to increases in crime by reducing economic opportunities for immigrants, particularly unauthorized immigrants.

This article provides an overview of the research on immigration, enforcement, and crime. As some politicians justify calls for tougher immigration enforcement by claiming it will improve public safety, it is vital for policy makers and the public to understand whether immigration in fact boosts crime and whether enforcement reduces the number of unauthorized immigrants and thereby reduces crime rates. The article begins with a summary of the research on immigration and crime. It then turns to the research on whether increased border enforcement reduces unauthorized immigration and crime. It next explores several other policies related to immigration and crime and concludes with a discussion about the likely effects of recent policy initiatives and about areas for further research.

2. Evidence on Immigration and Crime

Standard economic theory predicts that criminal behavior is related to opportunity costs. Becker (1968) first formalized the idea that potential criminals consider the expected costs and benefits of committing crimes before they engage in criminal behavior. The greater the expected costs are in terms of forgone labor market opportunities (employment and earnings) and harsher punishment, the less likely they are to commit crimes.

Applied to immigrants in the US, this theory gives countervailing predictions. On the one hand, immigrants may be more likely to commit crimes because they typically have lower earnings than similar US natives. And since immigrants tend to be younger and disproportionately male—characteristics associated with criminal behavior—they may be more likely to commit crimes than the average US native. On the other hand, some immigrants who commit crimes face much stiffer punishments than US natives if they are caught. In addition to imprisonment, noncitizen immigrants can be deported if they are convicted of a serious crime, barred from reentering the US, or deemed ineligible to become naturalized citizens. This heightened deterrence effect predicts that immigrants are less likely than US natives to commit crimes.

The empirical evidence comes down decidedly on the side of immigrants being less likely to commit crimes. A large body of empirical research concludes that immigrants are less likely than similar US natives to commit crimes, and the incarceration rate is lower among the foreign-born than among the native-born (see, for example, Butcher and Piehl 1998a, 1998b, 2007; Hagan and Palloni 1999; Rumbaut et al. 2006). Among men ages 18 to 39—prime ages for engaging in criminal behavior—the incarceration rate among immigrants is one-fourth the rate among US natives (National Academies of Sciences, Engineering, and Medicine 2015).

There are several potential reasons why immigrants are less likely than similar US natives to commit crimes despite their worse labor market prospects. First, the difference in the deterrence effect outlined above may dominate the difference in economic opportunities. Since noncitizens potentially face deportation, they should be more responsive than US citizens to crime-deterrence policies, such as increased police presence. Immigrants also may be subject to more scrutiny by law enforcement officers. But other channels besides deterrence may contribute to immigrants’ relatively low propensity to commit crimes. Immigrants may be positively selected from the population in their origin countries: people who are more likely to commit crimes may be less likely to become international migrants (Butcher and Piehl 1998a, 2007). Relatedly, US immigration policy may screen out some migrants who would commit crimes. Immigrants may be more likely to have close family and community ties, which tend to reduce the propensity to commit crimes (Sampson, Morenoff, and Raudenbush 2005; Ousey and Kubrin 2009).

There is some evidence that the lower propensity of immigrants to commit crimes does not carry over to immigrants’ children. The US-born children of immigrants—often called the “second generation”— appear to engage in criminal behavior at rates similar to other US natives (Bersani 2014a, 2014b). This “downward assimilation” may be surprising, since the second generation tends to considerably outperform their immigrant parents in terms of education and labor-market outcomes and therefore might be expected to have even lower rates of criminal behavior (National Academies of Sciences, Engineering, and Medicine 2015). Instead, immigrants’ children are much like their peers in terms of criminal behavior. This evidence mirrors findings that the immigrant advantage over US natives in terms of health tends to not carry over to the second generation (e.g., Acevedo-Garcia et al. 2010).

Although immigrants are less likely to commit crimes than similar US natives, they are disproportionately male and relatively young—characteristics associated with crime. Does this difference in demographic composition mean that the average immigrant is more likely than the average US native to commit crimes? Studies comparing immigrants’ and US natives’ criminal behavior and incarceration rates tend to focus on relatively young men, leaving the broader question unanswered. However, indirect evidence is available from looking at the relationship between immigration and crime rates. If the average immigrant is more likely than the average US native to commit crimes, areas with more immigrants should have higher crime rates than areas with fewer immigrants.

The evidence here is clear: crime rates are no higher, and are perhaps lower, in areas with more immigrants. An extensive body of research examines how changes in the foreign-born share of the population affect changes in crime rates. Focusing on changes allows researchers to control for unobservable differences across areas. The finding of either a null relationship or a small negative relationship holds in raw comparisons, in studies that control for other variables that could underlie the results from raw comparisons, and in studies that use instrumental variables to identify immigrant inflows that are independent of factors that also affect crime rates, such as underlying economic conditions (see, for example, Butcher and Piehl 1998b; Lee, Martinez, and Rosenfeld 2001; Reid et al. 2005; Graif and Sampson 2009; Ousey and Kubrin 2009; Stowell et al. 2009; Wadsworth 2010; MacDonald, Hipp, and Gill 2013; Adelman et al. 2017). The lack of a positive relationship is generally robust to using different measures of immigration, looking at different types of crimes, and examining different geographic levels.²The few academic studies that report a positive relationship do so when examining just Mexican immigrants, and even here the evidence is mixed. Spenkuch (2013) finds a positive relationship between changes in the Mexican immigrant share and property crime rates at the county level, but no significant relationship for violent crime rates. Chalfin (2014) does not find a significant relationship between changes in Mexican immigration and property crime or violent crime rates at the city level, while Chalfin (2015) finds that Mexican immigration is associated with a drop in property crimes and an increase in aggravated assaults at the metropolitan area level. Further, the lack of a positive relationship suggests that immigration does not cause US natives to commit more crimes. This might occur if immigration worsens natives’ labor market opportunities, for example.³Borjas, Grogger, and Hanson (2010) suggest that low-skilled immigration between 1960 and 2000 increased incarceration rates among African-American native-born men. However, Raphael and Ronconi (2008) show that this positive relationship does not hold up in state-level data, and conclude that immigration does not affect US natives’ criminal activity via increased labor market competition.

The few studies that examine crime among unauthorized immigrants have findings that are consistent with the broader pattern among immigrants—namely, unauthorized immigrants are less likely to commit crimes than similar US natives (apart from immigration-related offenses).⁴A study of self-reported criminal behavior among arrested youths in southern California finds that unauthorized immigrants report engaging in less crime before and after their arrests than legal immigrants or US natives (Bersani et al. 2018). A Cato Institute study of Texas Department of Public Safety data concludes that arrest and conviction rates among unauthorized immigrants are far below those among US natives, although rates among legal immigrants are the lowest (Nowrasteh 2018) Likewise, studies that examine the link between the estimated number of unauthorized immigrants as a share of an area’s population and crime rates in that area typically find evidence of null or negative effects.⁵Light and Miller (2018) find null or negative relationships between changes in state-level unauthorized immigration population shares and violent crime rates, while Light, Miller, and Kelly (2017) find that increases in unauthorized immigration are associated with reductions in drug arrests and DUI arrests. Green (2016) finds that the estimated share of a state’s population composed of unauthorized immigrants is not significantly related to its overall violent crime rate but is positively related to drugrelated crime rates. That study uses a single cross section of data and therefore is unable to control for unobserved state-level factors that may affect crime rates. Light, Miller, and Kelly (2017) and Light and Miller (2018), in contrast, use repeated cross sections and can control for such factors using state fixed effects.

While the small literature on the topic generally does not indicate that unauthorized immigration increases crime, the evidence does suggest that legal status matters. Areas in which more immigrants received legal status via the 1986 Immigration Reform and Control Act (IRCA) legalization program experienced larger reductions in their overall crime rate, driven by lower property crime rates (Baker 2015). Improved labor market opportunities among newly legalized immigrants led to the number of crimes falling by 3 to 5 percent. A study of one Texas county finds that alleged criminal behavior increased after IRCA among Hispanics living in neighborhoods composed largely of recent Mexican immigrants (Freedman, Owens, and Bohn 2018). The increase was concentrated in drug felonies and was presumably due to worse labor market opportunities for unauthorized immigrants since IRCA made it illegal to hire unauthorized immigrants.

Enabling more immigrants to adjust from unauthorized to legal status can reduce crime rates by increasing immigrants’ access to better jobs that pay higher wages. In contrast, making it harder for immigrants to work can lead to higher crime rates.⁶Studies from two European countries also indicate that legal status matters. Receiving legal status reduced arrest and recidivism rates among Bulgarian and Romanian migrants in Italy (Mastrobuoni and Pinotti 2015). In the UK, property crime rates rose in areas where more asylum seekers settled but fell in areas where more migrants from EU-accession countries settled (Bell, Fasani, and Machin 2013). The former did not have permission to work legally, while the latter did. Current policy makes adjusting to legal status difficult for most unauthorized immigrants, particularly those who entered the US illegally.⁷Most migrants must leave the US as part of the application process for a green card. This triggers a three- or ten-year bar to reentry for unauthorized immigrants who previously had entered the US illegally. Worksite enforcement policies, such as state laws requiring employers to use E-Verify to check that new hires are eligible to work in the US, make it harder for unauthorized immigrants to work.⁸See, for example, Orrenius and Zavodny (2015a). This worsens their labor market prospects and hence raises the net benefit of committing crime. We further discuss the effects on crime of these and other immigration policies below.

3. Effects of Border Enforcement on Immigration and Crime

Given the current focus on unauthorized immigration, border enforcement, and crime, it is important to understand whether border enforcement deters unauthorized immigrants and thereby reduces crime. US border enforcement has increased considerably over the past three decades. The ramp-up in border enforcement encompasses everything from personnel to fencing to motion detector cameras and aerial surveillance. The probability of apprehension along the border is estimated to have risen from 40 percent in 2000 to 55 percent by 2015 (Alden 2017). Penalties for illegal crossings have also increased, as has the ease with which penalties are meted out.⁹9 So-called “zero tolerance” and “consequence” policies implemented by the Border Patrol increased the share of apprehended migrants subject to administrative and criminal sanctions from 15 percent in 2008 to 85 percent in 2012 (Bazzi et al. 2018).

Recent years have seen a substantial decrease in the inflow of undocumented migrants concomitant with the increase in border enforcement. Indeed, the 304,000-some migrants apprehended along the USMexico border in fiscal year 2017 represent the lowest apprehension level since 1971.¹⁰See US Border Patrol, “Southwest Border Sectors: Total Illegal Alien Apprehension by Fiscal Year (Oct. 1st through Sept. 30th),” accessed February 22, 2019, https://www.cbp.gov/sites/default/files/assets/documents/2017-Dec/BP%20Southwest%20Border%20Sector%20Apps%20FY1960%20-%20FY2017.pdf. The best analysis available to date estimates that increased enforcement explains approximately one-third of the recent reduction in the inflow of undocumented migrants, and economic factors explain the remainder (Roberts, Alden, and Whitley 2013; Roberts 2017). The main way in which border enforcement deters crossings is by increasing the need to hire a smuggler and the cost of doing so.

Some researchers have pointed out that a perverse short-run effect of increasing border enforcement was a rise in the unauthorized immigrant population as circular migration declined (see, for example, Massey, Durand, and Pren 2016; Roberts 2017). Many migrants who used to periodically return home instead settled in the US and were joined by their families. As a result, the size of the unauthorized immigrant population living in the US continued to rise for at least a decade after the ramp-up in border enforcement began in earnest. However, the size of the unauthorized immigrant population has been stable or slightly smaller since the onset of the 2007–2009 recession. Estimates from the Pew Research Center indicate that the unauthorized immigrant population peaked at 12.2 million in 2007 and was about 10.7 million in 2016 (Passel and Cohn 2018). Tougher border enforcement, combined with increased interior enforcement, appears to be working in terms of reducing unauthorized immigrant inflows and ultimately the size of the unauthorized immigrant population.

But does this increase in border enforcement and resultant drop in unauthorized immigration result in less crime? The limited evidence available is mixed. A study of areas along the US-Mexico border finds that increases in apprehensions made by the US Border Patrol are positively related to violent crime rates but are not significantly related to property crime rates (Coronado and Orrenius 2007). Border Patrol linewatch hours—a measure of enforcement intensity—in a given border sector are not significantly related to violent crime rates in that sector, but linewatch hours in neighboring sectors are positively related to violent crime rates in a given sector (Coronado and Orrenius 2007). Increased enforcement in an area deflects some unauthorized immigrant inflows to other areas, apparently boosting violent crime in those areas. The increase in violent crime is likely related to migrants’ growing reliance on smugglers as border enforcement increases and to a concomitant rise in drug smuggling along the border.

4. Effects of Other Immigration Policies

Over the last two decades, the role of the criminal justice system in immigration has expanded considerably. In fact, the word “crimmigration” was coined to describe the intersection of criminal law and immigration law as the scope and importance of this nexus grew. The increased involvement of the criminal justice system in immigration began in earnest with two 1996 laws, the Illegal Immigration Reform and Immigrant Responsibility Act (IIRIRA) and the Antiterrorism and Effective Death Penalty Act, that laid the groundwork for many of the policies in place today. Among other provisions, those laws expanded the list of crimes for which immigrants could be deported and have their legal permanent resident status revoked. The IIRIRA also authorized the federal government to deputize state and local law enforcement officers to enforce immigration law. The resulting variation in policies over time and across areas, including the refusal of “sanctuary” jurisdictions to cooperate with federal immigration agencies, has enabled researchers to examine the effects of these policies on crime rates. As discussed below, the evidence tends to indicate that the increased involvement of state and local law enforcement in immigration enforcement has not led to lower crime rates

4.1 Federal Partnerships with State and Local Law Enforcement

There are three major programs in effect in the interior of the country that aim to identify and remove immigrants who pose a threat to public safety: the Criminal Alien Program (CAP), Secure Communities, and 287(g).¹¹For a more detailed explanation of CAP, Secure Communities, and 287(g), see Kandel (2016). As explained by Coon (2017), CAP involves identifying deportable immigrants— immigrants who are not US citizens and who are incarcerated in federal, state, and local prisons—and deporting them before they are released back into the community. Secure Communities enables law enforcement officers to compare biometric data to a Department of Homeland Security database when arrestees are booked into local jails. Immigration and Customs Enforcement (ICE) is notified when a potentially deportable immigrant is arrested and then begins an investigation and, if applicable, handles the deportation process.

ICE began rolling out Secure Communities in 2008, and the program was in place nationwide in 2013. The 287(g) program—named after the corresponding section of the Immigration and Nationality Act as amended by the 1996 IIRIRA—allows state and local law enforcement agencies to sign an agreement with ICE that delegates authority for immigration enforcement to these agencies. State and local law enforcement officers in participating jurisdictions can interview arrestees to ascertain their immigration status and potentially refer them to ICE for deportation. Under CAP, Secure Communities, and 287(g), immigrants must be incarcerated or arrested for some other crime before their immigration status is investigated.

Although deporting immigrants who commit violent crimes should increase public safety, the evidence suggests that these programs have had little effect. For example, studies that examine areas before and after they began participating in Secure Communities fail to find a significant increase in public safety as measured by crime and arrest rates (Miles and Cox 2014; Treyger, Chalfin, and Loeffler 2014).¹²Unpublished studies also fail to find evidence of a significant relationship between the presence of a 287(g) agreement or Secure Communities and crime rates (Pinheiro 2009; Forrester and Nowrasteh 2018). This is not surprising since relatively few of the immigrants deported via these programs pose a threat to public safety. Indeed, the vast majority—85 percent—of ICE removals under Secure Communities were for immigration offenses, including illegal entry, illegal reentry, and unlawful presence.¹³These data are based on TRAC immigration data. TRAC Immigration (website), “Removals under the Secure Communities Program,” accessed February 23, 2019, http://trac.syr.edu/phptools/immigration/secure/. One study found that only 3 percent of the 2.6 million immigrants ICE dealt with via CAP during 2010 to 2013 had been convicted of a violent or serious crime (Cantor, Noferi, and Martínez 2015). The vast majority had been convicted of a nonserious or nonviolent offense. About one-half of immigrants detained under the 287(g) program had committed only a misdemeanor or a traffic violation (Capps et al. 2011). Further, these programs may actually decrease public safety in some immigrant-intensive areas by making immigrants less willing to come into contact with law enforcement (Kirk et al. 2012; Theodore and Habans 2016). When immigrants are unwilling to report crimes or testify against offenders for fear of being deported, they become easier targets for criminals. More crimes may occur but a smaller share of them may be reported or successfully prosecuted, resulting in no change in official crime rates measured on a per capita basis but a decrease in actual public safety.

In part because of concerns about racial profiling and the limited effectiveness of the Secure Communities and 287(g) programs, the Obama administration scaled them back.¹⁴Since Secure Communities overlapped with many aspects of 287(g), ICE announced in 2012 that it would not renew any 287(g) agreements or enter into new ones. After the Obama administration discontinued Secure Communities in 2014, ICE resumed renewing 287(g) agreements and entering into new ones (Coon 2017). Secure Communities was discontinued in 2014 and replaced with the Priority Enforcement Program (PEP). PEP limited ICE to pursuing deportation only for immigrants who posed a demonstrable risk to national security or had been charged with or convicted of a particular set of crimes, including criminal gang activity. PEP also limited the scope of the 287(g) program. The Trump administration promptly reversed course. In January 2017, it issued executive orders terminating the Priority Enforcement Program, reinstating Secure Communities, and expanding the 287(g) program.

4.2 Sanctuary Jurisdictions

Some parts of the United States responded to the increase in interior enforcement exemplified by the 287(g) program and Secure Communities by adopting laws or ordinances that prohibit state or local government resources from being used to enforce federal immigration laws. The rationale for such laws has been to preserve trust in the police and encourage the reporting of crimes; to avoid the costs of complying with federal requests to detain suspects for longer; and to prevent the adverse impact on families and communities of deporting low-priority immigrants, often household heads with jobs and dependents. Critics, on the other hand, allege that these “sanctuary” policies protect immigrants who commit crimes and lead to an increase in criminal activity. However, studies show that crime rates are the same or lower in sanctuary jurisdictions compared with otherwise-similar jurisdictions, or before and after a given area enacted a sanctuary policy (Gonzalez, Collingwood, and El-Khatib 2017; Martínez-Schuldt and Martínez 2017; Wong 2017). In addition, the negative relationship between the immigrant population share and crime rates discussed above is stronger in sanctuary cities (Lyons, Vélez, and Santoro 2013; Martínez-Schuldt and Martínez 2017). Nevertheless, the Trump administration issued an executive order in January 2017 making areas that refused to comply with federal immigration enforcement policies ineligible for federal grants related to law enforcement.¹⁵The order (Executive Order No. 13768) has been enjoined by several courts and ruled unconstitutional by the Ninth Circuit Court of Appeals.

5. Discussion and Conclusion

US immigration policy aims to achieve a large set of goals: enable families to reunite, provide sanctuary to people fleeing persecution abroad, support economic growth by allowing firms to hire foreign workers, and advance US geopolitical interests. Immigration policy also aims to protect public safety and national security by barring and removing migrants who appear to pose a credible threat.

The use of immigration policy as a tool for protecting public safety and national security has increased dramatically over the last two decades. Some of these changes make sense. For example, 9/11 and other terrorist incidents demonstrated the need for more thorough screening of applicants for temporary and permanent visas and for more coordination among federal agencies and between US agencies and foreign governments. The tremendous growth in the unauthorized immigrant population during the 1990s through 2007 indicated the need to further increase immigration enforcement along the US-Mexico border. The subsequent increase in enforcement appears to have succeeded in dramatically reducing inflows of unauthorized immigrants, and the unauthorized immigrant population has been stable or falling for more than a decade. On the other hand, devoting more resources to building a wall or to removing large numbers of immigrants who have committed only a misdemeanor means fewer resources are available for other enforcement activities that might have a greater impact on public safety. Meanwhile, discussion of a legalization program has largely disappeared from the public agenda, but the evidence suggests that implementing a large-scale legalization program would lead to lower crime rates by improving migrants’ economic opportunities.

Several recent immigration policy initiatives by the Trump administration are unlikely to increase public safety and may even prove counterproductive. The evidence on Secure Communities indicates that the program did not lead to lower crime rates, yet the program has been resurrected in the name of reducing crime. The evidence on sanctuary cities indicates they do not have higher crime rates than other, similar areas, but the administration has proposed penalizing sanctuary jurisdictions. The best outcome would be for federal, state, and local governments to work together to craft enforcement policies that prioritize apprehending, incarcerating, and, if applicable, deporting serious criminals.

Other proposed or implemented policy changes that would affect unauthorized immigrants’ economic opportunities include ending the Deferred Action for Childhood Arrivals (DACA) program and ending the extension of Temporary Protected Status (TPS) to migrants from several countries. These programs have granted temporary legal status to over one million qualified migrants who would otherwise be unauthorized, enabling them to work legally and improving their economic opportunities and living standards.¹⁶For studies of the programs’ effects on participants’ economic outcomes, see, for example, Amuedo-Dorantes and Antman (2016) and Kuka, Shenhav, and Shih (2018) on DACA and Orrenius and Zavodny (2015b) on TPS. Participants lose their protected status if they are convicted of a serious crime, so the programs also have a deterrence component. There is no evidence about whether programs like DACA and TPS reduce crime, but their establishment and potential elimination creates variation that researchers should use to assess their effects on crime rates.

A crucial fact seems to have been forgotten by some policy makers as they have ramped up immigration enforcement over the last two decades: immigrants are less likely to commit crimes than similar US natives. This is not to say that immigrants never commit crimes. But the evidence is clear that they are not more likely to do so than US natives. The comprehensive 2015 National Academies of Sciences, Engineering, and Medicine report on immigration integration concludes that the finding that immigrants are less likely to commit crimes than US natives “seems to apply to all racial and ethnic groups of immigrants, as well as applying over different decades and across varying historical contexts” (328). Unauthorized immigrants may be slightly more likely than legal immigrants to commit crimes, but they are still less likely than their US-born peers to do so. Further, areas with more immigrants tend to have lower rates of violent and property crimes. In the face of such evidence, policies aimed at reducing the number of immigrants, including unauthorized immigrants, seem unlikely to reduce crime and increase public safety.

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