Researchers Examined 11,500 US Neighborhoods and Found No Link Between Crime and Illegal Immigration

For decades, one of the biggest arguments surrounding illegal immigration has centered on a simple fear: does a growing undocumented population make the places around it more dangerous? Politicians have spent years making public safety a central part of the immigration debate, while billions of dollars have been committed to border security and enforcement. Now, one of the largest studies of its kind has taken that question down to the level where people actually live, examining thousands of individual neighborhoods across the United States.

The result is unlikely to quiet the political argument anytime soon. But the researchers found no evidence that neighborhoods with growing undocumented populations became more dangerous overall. Property crime fell further in those areas, violent crime showed no significant increase, and aggravated assaults declined. The findings add fresh detail to a debate that has been running for generations, reaching all the way back to a federal investigation conducted nearly a century ago.

Researchers Studied 11,500 Neighborhoods Across America

A team at the University of California, Irvine examined approximately 11,500 neighborhoods across more than 100 American cities between 2010 and 2018. The study covered roughly 46 million residents and focused on a question previous research had struggled to answer at such a local level: what happens when the undocumented share of a specific neighborhood increases?

Across the full period, the estimated undocumented share of residents declined overall, falling from around 5.6% in 2010 to 4.8% in 2018. The researchers then examined neighborhoods where the pattern moved in the opposite direction. They wanted to know whether places that experienced an increase in undocumented residents also experienced a rise in crime.

According to the study, the answer was largely no. Property crime declined more in neighborhoods where the undocumented population increased. Violent crime showed no statistically significant change, while aggravated assault declined significantly. Lead author Charis E. Kubrin, a Chancellor’s Professor at UC Irvine, said: “Consistent with the research base more generally, unauthorized immigration does not drive crime rates in U.S. neighborhoods.” She added: “Honestly, I wasn’t too surprised.”

The scale of the research is what separates it from many earlier studies. Previous work had examined entire states, metropolitan areas, or cities. This research moved much closer to the places where residents form their strongest opinions about safety: their streets, blocks, and immediate communities.

Why Researchers Went Down To Street Level

The team faced a major challenge before the research could even begin. The data required to estimate undocumented populations at the neighborhood level is not publicly available in the way ordinary Census information is. Researchers worked inside a secure federal Research Data Center, where restricted Census records can be accessed under strict supervision.

Co-author Derek Christopher, now at Stanford University, adapted an existing statistical approach to estimate how many people in individual neighborhoods were likely to be undocumented. He explained that the broader methods behind such estimates have existed for decades because directly counting a population that is intentionally difficult to identify presents obvious challenges.

But Christopher said the neighborhood-level question was particularly important because it reflected the concern he continued to hear from people. “While previous studies are clear about the broader relationship between immigration and crime, say, for city crime rates, none has really adequately addressed the concern I still hear along the lines of, ‘but should I be worried about illegal immigration in my neighborhood, specifically?’” he said.

Kubrin also stressed that neighborhoods are where public perceptions take shape. A national statistic can feel distant, but the people living on a particular street are often concerned with what is happening within walking distance of their homes. That was the gap this research attempted to close.

One Crime Category Did Move Up

There was one result that stood apart from the others. Robberies increased in neighborhoods where the estimated undocumented population grew, even as several other crime categories declined or remained unchanged.

The researchers said the finding should not automatically be interpreted as evidence that undocumented immigrants were committing more robberies. Instead, they suggested the opposite possibility: undocumented residents may be disproportionately targeted by robbers.

Co-author John Hipp said: “An increase in robberies, despite decreases in all other crime categories, would be consistent with the idea that undocumented immigrants are disproportionately likely to be targets of robbery given greater involvement in the cash economy.”

The explanation centers on financial vulnerability. People without access to traditional banking may be more likely to receive wages in cash or carry cash with them. At the same time, someone worried about their immigration status may be less willing to report a crime to authorities. That combination could make certain individuals more attractive targets.

However, the researchers were careful not to present that explanation as proven fact. Police records do not identify whether a robbery victim is undocumented, meaning the study could not directly establish who was being targeted. The explanation fits the pattern, but the available data cannot confirm it.

The Study Has Limits Researchers Could Not Ignore

Research involving undocumented populations comes with a problem that cannot be completely eliminated: nobody has an exact list of every undocumented resident in the country. Every estimate depends on statistical methods designed to identify likely gaps in official population records.

The researchers openly acknowledged that limitation. Alexis Piquero, a criminologist at the University of Miami who was not involved in the study, noted that measuring undocumented populations is difficult precisely because people without legal status can be hard to identify through traditional government records.

Kubrin defended the reliability of the estimates by pointing out that the team’s figures were broadly similar to estimates produced by the Department of Homeland Security. Even so, the numbers remain estimates rather than a direct count.

There is another important limitation. The study tracked how crime changed alongside changes in the estimated makeup of neighborhoods over nine years. That creates a powerful picture across a huge sample, but it does not prove that one factor directly caused another.

The researchers identified associations between population changes and crime trends. Other economic, social, demographic, and local factors could also influence what happens in any particular neighborhood.

The Immigration Debate Now Carries A Massive Price Tag

The timing of the research has added another layer to the debate. Immigration enforcement has become one of the most heavily funded areas of federal policy, with Congress committing roughly $170 billion to the Department of Homeland Security for immigration and border enforcement through a major 2025 law, according to the figures cited in the research surrounding the issue.

That spending has been justified partly through arguments about crime and public safety. For Kubrin, that is precisely why examining the evidence at the neighborhood level was necessary.

“It’s well beyond time to rethink immigration enforcement in this country,” she said. “These policies are largely ineffective at enhancing public safety and may actually do more harm than good.”

Her conclusion was even more direct: “With policies like these, no one wins.”

The study does not attempt to settle every political question surrounding immigration. It focuses on one specific claim that has repeatedly shaped public policy: whether an increase in undocumented immigration is associated with higher crime in the communities where people live.

Across thousands of neighborhoods, the researchers did not find evidence supporting that argument overall.

Similar Research Has Pointed In The Same Direction

The UC Irvine findings do not exist in isolation. Kubrin pointed to a much older chapter in American history that reached a similar conclusion.

In 1931, a federal commission released a report examining crime and foreign-born populations in the United States. Social scientist Edith Abbott had worked through arrest records and court data in cities including New Orleans, San Francisco, and Stockton, California, as researchers attempted to answer many of the same questions still being argued today.

Kubrin noted that the Wickersham Commission’s work found lower involvement in crime among immigrants than among native-born Americans. Research from outside the United States has also produced findings that broadly fit the same pattern.

Ben Brindle, a senior researcher at the Migration Observatory at the University of Oxford, said the American findings were consistent with research conducted in the United Kingdom. “That very much fits the picture that we’ve seen in UK studies,” he said.

The new study’s contribution is its resolution. Instead of stopping at the level of a state or an entire city, researchers looked much closer to home. They examined the neighborhoods where residents actually experience changes in population and where fears about safety often become most personal.

What The Numbers Actually Show

The findings can be boiled down to several key results:

• Property crime: Declined further in neighborhoods where the estimated undocumented population increased.
• Violent crime: Showed no statistically significant increase.
• Aggravated assault: Declined significantly in those neighborhoods.
• Robbery: Increased, although researchers said undocumented residents may have been disproportionately targeted.
• Overall pattern: The study found no evidence that growing undocumented populations drove higher neighborhood crime rates.

That does not mean immigration is no longer a political issue, or that every concern surrounding border policy disappears with one study. Immigration involves questions about enforcement, labor, asylum, government resources, and national policy.

But when researchers examined one of the most persistent public safety claims at the scale of individual American neighborhoods, the expected surge in crime did not appear.

Nearly 100 years after Edith Abbott examined arrest records and court documents for a federal commission, researchers are still testing the same fear with far more data and far more advanced methods. The technology has changed. The politics have changed. The scale of immigration enforcement spending has changed.

The central finding, however, has remained remarkably consistent: the neighborhoods gaining undocumented residents were not the neighborhoods becoming more dangerous.