Who says recessions are all bad? About 5,000 fewer people die every year in auto accidents for each 1 percentage point increase in U.S. unemployment because downturns keep dangerous drivers off the road.

“We have documented an instance of a natural economic force that impels riskier drivers to drive less while not discouraging safer drivers,” say Clifford Winston, a senior fellow at Brookings Institution, and Vikram Maheshri, an economist at the University of Houston, in a forthcoming study in the Journal of Risk and Uncertainty.

Previous research had shown that people generally drive less during economic contractions, which naturally contributes to a reduction in fatalities. The innovation by Winston and Maheshri was to show that the biggest decline is in driving by the worst drivers.

Those who took to the road less often as unemployment rose included drivers who nevertheless had accidents during the course of the study. It also included drivers who have older cars, who are over the age of 60, and those living by themselves or with only one other person (who tend to have higher accident rates than family heads). 

The researchers didn’t have strong evidence to conclude why these particular groups drove less. One theory is that people with lower incomes were more likely to lose their jobs and not need to commute to work. Those people might be more likely to have older cars and to live alone. Commuting can’t be the whole story, though, since such trips account for only about 20 percent of driving, according to Winston.

Additionally, the researchers didn’t have direct data on whether the people in the survey were employed, or what their incomes were. The data came from customers of insurer State Farm in Ohio who agreed to have their travels electronically recorded in return for a cut in their rates. The period covered was from August 2009, when the national recession was technically over but joblessness remained high, through September 2013.

The study found that auto fatalities in Ohio were 14 percent lower when the jobless rate was 1 percentage point higher; the national figure of roughly 5,000 saved lives comes from projecting that to the national auto fatality toll of around 33,000 a year.

“In all fairness, this is by no means definitive. This is clearly a first cut,” Winston said in an interview.

One intriguing question is how the U.S. could get dangerous drivers off the road without having to suffer through a recession. Driverless cars would help, the authors write. For example, Winston said a lot of mayhem is caused by drivers with suspended licenses. Driverless cars would give them a way to get around without getting behind the wheel. The research was supported by the AAA Foundation for Traffic Safety.