During precisely the period that California experienced the biggest immigrant population increase in its history, the state also experienced a precipitous drop in crime rates, according to a report by Barry Krisberg, a renowned criminologist at UC Berkeley's School of Law.
In fact, in counties closest to the border where you would expect to see the largest increases in crimes, there were huge drops. In San Diego County, its violent crime rate declined by 58 percent between 1991 and 2008, while in Imperial County, the violent crime rate dropped by 53 percent and serious property crime rate by 13 percent.
In Los Angeles County, which saw its foreign-born population increase by 1.2 million, violent crime dropped by 68 percent and serious property crime by 42 percent. Other Southern California counties, as well as Central Valley counties such as Kern County, experienced similar drops.
Krisberg points out that these outcomes are consistent with the conclusion of a 2008 Public Policy Institute of California report [PDF] which found that increased immigration was correlated with declining rates of violent crime. In fact, research in Chicago went one step further and "actually concluded that immigrants were responsible for a drop in crime."
Contrary to public perceptions, Krisberg also points to how immigrants are vastly underrepresented in California prisons. Noncitizens make up 27 percent of California's population – but only 11 percent of its prison population. That underrepresentation seems to apply to illegal immigrants as well. The federal Immigration and Customs Enforcement places "holds" on foreign-born inmates eligible for deportation. But over the past decade, as the state's prison population rose by 3 percent, the number of "holds" placed by ICE in California actually declined by 14 percent.
In fact, the PPIC report cited above notes that foreign-born California residents are incarcerated at a rate of 161 per 100,000, compared to a rate of 259 per 100,000 for U.S.-born Californians.
Those figures are at odds with the assertion by gubernatorial candidate Meg Whitman that 30 percent of state prison inmates are illegal immigrants, a figure disputed by the California Department of Finance.
What's more, the same PPIC report shows that Mexican-born men, who constitute by far the largest share of California's male immigrant population, are "dramatically underrepresented in California prisons and other institutions."
Here are Krisberg's conclusions in this compelling paper:
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 American citizens is harmful. California is facing a myriad of serious social and economic challenges in the years ahead. The danger is to fall prey to … turning meaningful conversations about policy issues into opinions based on fear, myths, and political manipulation.