Throughout his topsy-turvy campaign, one thing that Donald Trump has actually been consistent on is immigration. Deport the 11 million undocumented immigrants living here. Ban Muslim migrants, too. And maybe the greatest hit of all: Build a big, beautiful wall between the U.S. and Mexico, since Mexican migrants are “rapists,” “drug dealers,” and “criminals.”
But contrary to the narratives advanced by Trump and his nativist peers, there’s tons of criminological research suggesting that immigration doesn’t bring crime. It stops it. While no one knows precisely why the national crime rate has cratered in the past 30 years — today, it’s at about half of the peak in 1991 — lots of scholars think that immigration is a big cause. Since the Immigration Act of 1965, some 59 million immigrants have come to the U.S., now accounting for 13.7 percent of the population. And they may be the main reason America is being made safe again.
In a 2007 working paper from the National Bureau of Economic Research, researchers analyzed the 1980, 1990, and 2000 censuses and found that each year, young men — the most crime-prone demographic — who were immigrants had lower incarceration rates than the native-born. The margin widened every decade, and by 2000, the institutionalization rate of immigrants was 20 percent of that of the native-born. Analyzing the 2010 census, among men aged 18 to 39 without a high-school diploma, native-born Americans had a 10.7 percent incarceration rate, while Mexican men had a 2.8 percent rate, and both Salvadoran and Guatemalan men had a 1.7 percent rate. Adding it up, while 3.3 percent of native-born young men were in jail in 2010, it was just 1.6 percent for immigrant males. Research indicates that when you adjust for personal backgrounds, first-generation immigrants are 45 percent less likely to commit a violent act than third-generation immigrants, while the second generation is 22 percent less likely to commit violence than the third.
The effect that immigrants have on cities appears to be significant. A 2010 study of cities of over 50,000 people found that the cities across the U.S. that received the most immigrants from 1990 to 2000 experienced the greatest drops in murder and robbery rates. In a 2010 study, a team lead by Northeastern criminologist Ramiro Martinez did a longitudinal analysis of homicides in San Diego neighborhoods from 1980 to 2000. Martinez and his colleagues found that areas with lots of immigrants saw reductions in violence over time, with a noted decline in homicides. Harvard sociologist Robert Sampson has found that the more languages that were spoken in a given neighborhood in Chicago in the 1990s, the fewer homicides there were from the 1990s to 2006.
New York City — where two million immigrants have arrived since the 1980s — is a case study: An analysis of immigration trends in the city from 1975 to 2013 found that for every 1-percent increase in the immigrant population for a given precinct, 966 fewer crimes were committed per year on average. New York is also a case study in how immigrants vitalize a place. In 2006, the average income of blacks passed that of whites in the borough of Queens, attributable to the swelling increase of people moving there from the West Indies. And that 1975-to-2013 analysis found that immigrants are “responsible for a $188 billion boost to home equity citywide,” especially outside of Manhattan. Indeed, in 2008, according to the report, immigrants accounted for about a third of the urban center’s gross product — a cool $215 billion.
Economist John Roman, formerly a senior fellow at the Urban Institute, tells Science of Us that immigrants change the culture of entire neighborhoods. Specifically, he says midsized cities like D.C., Baltimore, and Philadelphia have greater rates of home-ownership among relatively poor people, and if you own a row house in D.C. that gentrifies rapidly, you could create a ton of wealth (importantly, this is a form of economic mobility that isn’t dependent on income, but rather property). And while urban rehabilitation programs might target the city core from the top down, gentrification grows from the bottom up in areas the municipal government may be overlooking. “You can go to Baltimore and go to where Freddie Gray was killed,” he tells Science of Us, “and some of the housing stock is three-story row houses that are twice as wide as anything you’d see in New York or Philadelphia — it’s beautiful property and it’s been completely abandoned, in a neighborhood that’s been completely segregated and isolated racially.” (And segregation and isolation, criminologists know, is a prime driver of violence — look at Chicago.) But according to Roman, if you’re a member of a new immigrant class, it might be attractive to you: near the city core, with fantastic, if neglected, housing. “You get a property that is exceptionally undervalued compared to the rest of the region,” he says, “and as a place to start out as a multifamily or multigenerational dwelling, it’s extremely attractive.” Then the economic engines start firing. There’s all this nice housing stock, and then the neighborhood, with the mix of populations, begins to look and feel safer. Then come the gentrifiers. Then more investors. And more investors. Soon enough, you live a 12-minute walk from Whole Foods. “If I’m going to gentrify, what I want to see is a lot of recent immigrants,” Roman says. “That’s a strong signal to me to buy.”
That’s why, he says, the smartest cities have becoming really welcoming to immigrants. In the early 1990s, as immigration was starting to roll into Washington — accounting for half the District’s population growth from 1990 to 2000 — the relationship between the city and immigrants was punctuated by broken-windows-style policing, leading to riots in 1991. But since then, the city has put in effort to make itself available to recent immigrants, many of them from Latin America; for instance, you can do all your business with the District in Spanish (as well as in Chinese, French, Korean, Vietnamese, or the Ethiopian language Amharic). In New York, all city agencies offer translation into Spanish, Chinese, Korean, Russian, Italian, or Haitian Creole. It’s a sign of how when you consider the data, reducing crime isn’t just matter of more or fewer cops. It’s more and more immigrants.