What's Behind the Dramatic Drop in Highway Fatalities?

July 1, 2009 — -- The dramatic decline in highway deaths in the United States in the past couple of years is the result of multiple factors, not just a reduction in driving or because of high fuel prices, according to new research from the University of Michigan.

The higher cost for fuel is the dominant factor, of course, but it has precipitated a change in driving habits, including less leisure and rural driving, both of which are more dangerous than urban driving, according to Michael Sivak of the university's Transportation Research Institute. Sivak published his findings in the June issue of the journal Injury Prevention.

"The reduction in road fatalities is the result of a change not only in the amount of driving, but also in the type of driving," Sivak said.

Road fatalities in the United States decreased in all months but one from January 2007, through December 2008, the latest month for which statistics are available. The National Safety Council has reported a continual decline in motor vehicle deaths of about 9 percent per year across the country. The decline occurred in 40 states and the District of Columbia, but several large states were not included in the study.

Most experts have attributed the decline to the lousy economy, which has caused many to reduce driving and stay closer to home, at a time when fuel prices have sometimes hovered around $4 per gallon, though they have since declined. But Sivak took a closer look, examining the correlation between distance driven, proportion of driving on rural roads, and the average price of gasoline.

Since people are more likely to give up leisure driving than commuting to work during a time of economic difficulty, the price of gas led to a much greater reduction in leisure driving, according to Sivak's study.

Those three variables accounted for 81 percent of reduction in road fatalities, Sivak said. Other factors include increased "vigilance" by law enforcement, according to the Governors Highway Safety Association, and the simple fact that more people are wearing seat belts. According to the association, seat belts are probably worn by 90 percent of vehicle occupants these days, although that's difficult to measure.