Daniel Griswold at Cato's blog looks at some numbers, and some suppositions:
One of the clinching arguments for Arizona’s tough new law aimed at illegal immigration has been the perception in that state that crime has been rising, and that undocumented workers are largely to blame. Yet...the incidence of violent crime in Phoenix last year plunged 16.6 percent compared to 2008, a rate of decline that was three times the national average.
According to the Phoenix Police Department, the downward trend in crime has continued into 2010 even as the “illegal immigrant crime wave” story reverberates on cable TV and talk radio.
The Wall Street Journal story that Griswold relied on. Americans appear to be weathering this recession without an increased resort to violent crime. Who says Hit and Run never focuses on the good news?