It's official: It's a tough time to be a criminal in America.

As new FBI crime figures point out, property crimes, murder, rape, and arson all plunged in the first six months of 2010 – some would say counterintuitively – even as unemployment and hard times hit communities from coast to coast.

The idea that the crime rate is, if not a leading indicator, at least a trailing indicator of the economy has gripped criminologists studying the Great Recession. At the same time that consumers purchase fewer true luxury items, a glut of "lightweight durables" means lower resale prices for hot computers and wide-screen TVs. And having more male residents of households hanging on the porch instead of at work makes the risk-benefit analysis of crime less appealing in recessionary times.

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"When the economy goes down, there's less to steal, people are home more, and they get drunk in bars less," says Marcus Felson, a criminologist at Texas State University, in San Marcos.

"Recessions actually tend to be associated with decreases in crime," adds Peter Scharf, a criminologist at Tulane University in New Orleans. "People's aspiration levels go down, they get less greedy, they stay home. Not only don't you go to Saks and Macy's, you don't go to Best Buy and Walmart. So even in your risk populations you can get a recession effect: People are not out in the large economy involved in conflict and alcohol and property crimes" to the same extent as during a booming economy.

Nationwide, the six-month report shows reports of murder down 7.1 percent, rape reports down 6.2 percent, robbery reports down 10.7 percent, and aggravated assault reports down 3.9 percent. The data show a similar downward trend in reports of property crimes, with theft down 2.3 percent, motor vehicle theft down 9.7 percent, and arson down 14.6 percent.

To put the crime rate into context, Mr. Felson says, Americans should realize that the US is a society with few hard-core criminals but lots of occasional lawbreakers – in other words, regular citizens. What's more, he says, the difference between "perpetrator" and "victim" is far less stark than what most people believe.

"The fact is, a majority of the population does a little crime, and when you've got millions of Americans doing a little crime what you get is a giant multiplier," says Felson. "Crime is actually very ordinary and most crime isn't murder, and most assaults are minor. That means that the public image of crime is almost totally skewed."

So what about regional differences? Violent crimes actually ticked up slightly in the Northeast compared with in the South and West, but that statistic is largely explained by the fact that the baseline crime rate in the Northeast is lower than in other regions, so variances seem more significant.

At the same time, says Mr. Scharf, Southern states have been more reluctant to parole prisoners to ease overcrowding in prisons or to trim budgets. That means "that we've actually eroded some criminal-justice capacity, and that's most obvious in the North and less obvious in the South," he says.

At some point, the correlation between a poor economy and plunging crime rates may diverge, experts say.

"If we go for another couple of years and the New Orleanses and Atlantas out there can't absorb these [idle] kids into the economy, that's a huge long-term crime risk," says Scharf.

But for the moment, the plunging crime rate may have a simple explanation, he adds: "There's nothing left worth stealing."

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