There's also a driving gender gap. In a role reversal, there are now more women than men in the U.S. with driver's licenses. And the declines in miles driven over the past decade were more widespread among men than women, according to Pickrell and Pace. Driving by men has declined in every age group except those 65 or older, where it increased slightly. Among women, driving declined only among young adults and teenagers.
There are several economic factors that help explain the trends. Driving declines exactly mirror job losses among men during the recession, when male-dominated industries like manufacturing and construction were especially hard hit, researchers said. But average automobile use has declined recently even among those who have remained employed.
Economists say many Americans, especially teens and young adults, are finding that buying and owning a car stretches their financial resources. The average price of a new car is $31,000, according to the industry-aligned Center for Automotive Research in Ann Arbor, Mich.
"We're not selling to everyone. We're selling to upper-middle class to upper class," said Sean McAlinden, the center's chief economist. The rest of the public, he said, buys used cars or takes the bus.
Then there's the cost of insurance, maintenance and parking. The price of gas has gone up dramatically over the past decade.
The share of younger workers who can find jobs is at an especially low ebb, while the cost of a college education — and with it student loans — is soaring. Many schools have stopped offering free driver's education to students. Owning a car is increasingly beyond the reach of many young drivers, researchers said.
Research by the AAA Foundation for Traffic Safety found that 18- to 20-year-olds were three times more likely to have a driver's license if they lived in a household with an annual income above $100,000 than if they lived in a household with an income below $20,000.
"I don't think it's a change in people's preferences. I think it's all economics," McAlinden said. "It might last if the economics stay the same. But if they improve, I think people will come back to driving more. ... Give a person a good job 25 miles away and they'll be at the dealership the next morning."
The decline in driving has important public policy implications. Among the potential benefits are less pollution, less dependence on foreign oil, reduced greenhouse gas emissions and fewer fatalities and injuries. But less driving also means less federal and state gas tax revenues, further reducing funds already in short supply for both highway and transit improvements. On the other hand, less driving may also mean less traffic congestion, although the impact on congestion may vary regionally.
Phineas Baxandall, senior analyst for the liberal U.S. Public Interest Research Group, says driving declines mean transportation dollars could be put to other uses.
"You just don't want to spend money you don't have for highways you don't need," he said.
Follow Joan Lowy on Twitter at http://www.twitter.com/AP_Joan_Lowy
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