Protesters wave flags in front of an effigy of Donald Trump in Los Angeles. Lucy Nicholson/Reuters

New research contradicts President Trump’s claim that these areas do "immeasurable harm" to their residents.

On Wednesday, President Donald Trump announced two executive orders to jumpstart his immigration agenda. In one of them, he asked “sanctuary cities”—jurisdictions that legally limit their local police from collaborating with federal immigration authorities—to stop doing so, or else, lose federal funds. Per the order:

Sanctuary jurisdictions across the United States willfully violate Federal law in an attempt to shield aliens from removal from the United States. These jurisdictions have caused immeasurable harm to the American people and to the very fabric of our Republic.

The harm the order refers to is a decline in public safety. But that decline doesn’t appear to exist. To the contrary: Sanctuary cities show lower crime and higher economic well-being, a new analysis published by the Center for American Progress and the National Immigration Law Center shows.

In the report, Tom K. Wong, an associate professor of political science at the University of California, San Diego, analyzed a sample of 2,492 counties from an Immigration and Customs Enforcement (ICE) dataset. In this sample, 602 were identified by ICE as “sanctuary” counties, where local law enforcement didn’t accept “detainers”—requests from ICE to hold suspected undocumented individuals in custody for extra time. Wong compared the crime rates and economic conditions in these counties with the ones that did comply with ICE, controlling for population and demographic characteristics.

He found 35.5 fewer violent and property crimes per 10,000 people in sanctuary counties versus non-sanctuary ones—“a result that is highly statistically significant.” Counties in large metros reported an even more dramatically difference, with 65.4 fewer crimes per 10,000 people.

Sanctuary counties also registered better economic conditions. On average, they had higher median incomes (by about $4,353), lower poverty (by 2.3 percent), and slightly lower unemployment rates (1.1 percent). These positive effects were exaggerated in the small counties, where the contributions of each individual immigrant were likely to have a larger impact.

Wong concludes:

The data support arguments made by law enforcement executives that communities are safer when law enforcement agencies do not become entangled in federal immigration enforcement efforts. The data also make clear that, when counties protect all of their residents, they see significant economic gains. By keeping out of federal immigration enforcement, sanctuary counties are keeping families together—and when households remain intact and individuals can continue contributing, this strengthens local economies.

Wong’s analysis is not the first to contradict this administration’s narrative on sanctuary cities. A previous study examined crime rates over time in these areas. Some, like San Francisco, experienced a rise in crime after the fact; others, like Baltimore, saw the opposite effect. On average, the researchers observed no “statistically significant effect” on crime after these cities enacted sanctuary-type policies.

Like in any other group of people, undocumented immigrants do contain some people who commit serious crimes—but they make up a small minority, according to a 2012 congressional report.* Still, some opponents maintain that these cities pose a threat to their residents. But there are mayors on both sides of the political aisle who have argued that conflating policing with immigration enforcement leads to a breakdown in the community trust—a claim that research has backed up. They argue that “sanctuary cities” do cooperate with authorities do deport violent criminals, just in a way that doesn’t jeopardize the relationship local police have with immigrant populations. Wong’s findings support their case: Cities where immigrant communities trust authorities to report crime are safer and more productive.

*This post has been updated.

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