UC Berkeley Study: California Crime Rates Unrelated to Immigration

A new study from the University of California at Berkeley challenges a widespread assumption that has become an article of faith in nativist circles: that immigration has fueled a crime wave of epic proportions, one that calls for militarization of the border and measures like the ill-conceived and ill-fated Arizona law that would have made local police into de facto agents of the federal immigration authorities.

The Berkeley study focuses on California – the state with the largest foreign-born population in the country – mapping violent crime statistics against immigration statistics for the state and for several counties, and finding that “during a long period of new immigration, crime has shown a large and steady decline in California.” (See Where is the Fire? Immigrants and Crime in California (PDF, 251KB), by Barry Krisberg, with the assistance of Veronica Smith, Berkeley Center for Criminal Justice, 01.Oct.2010.)

According to California Department of Finance figures cited in the study, an estimated 3,667,886 foreign-born people migrated to California during the period in question, 1991-2008, of whom about one-third were unauthorized immigrants. Contrary to the rhetoric of anti-immigrant fear mongers, the growing immigrant population did not trigger a crime wave; the study makes this clear, charting the statewide decrease in crime against immigration trends that rise and fall without any effect on the incidence of violent crimes. At the county level, the peaks of one trend line often correspond only to a trough in the other one. As the study notes:

“During the 1991-2008 timeframe, there was a dramatic decline in California in crimes reported to the police. The violent crime rate (per 100,000 residents) including homicide, rape, robbery and aggravated assault dropped by 55 percent over the past 18 years. Figure 1 shows the contrasting trends in foreign-born immigration and violent crime rates during these two decades. Serious property crime rates including auto theft, grand larceny, burglary and arson also declined by 29 percent from 1991-2008.”

These statistical trends hold true even at the county level, whether one looks at crime rates in the border jurisdictions of San Diego and Imperial counties, or hugely populous Los Angeles county. The study’s authors are careful to point out that there is no correlation between increased immigration and falling crime rates. Nonetheless, their statistical comparison decisively undermines the claims of many California politicians and activists who claim that immigration increases crime, or causes violent crime. They strike a cautionary note in their concluding remarks:

“The data in this paper confirm that there is no evidence that California is in the midst of a crime emergency as a result of substantial migration of persons born in other nations. To allow this myth to guide public policy discussions about newly arrived noncitizens and future Americans is harmful.”

No argument here.