When Leslie Norrington moved from Arlington, Va., to Adams Morgan in northwest Washington, D.C., a month ago, she brought all of her belongings. But not her car.

"I don't need it. My apartment is just over a mile from my office, so I walk every day," she said. While Norrington, 25, still has her car in Virginia, it likely won't be hers for much longer. "I think I might give it to my parents," she said.

Trends indicate that Norrington, who works in marketing for the nonprofit American Legacy Foundation, is one of many Americans who have recently decided to use their cars less, sell them or not buy one in the first place. Whether motivated by convenience, cost or other phenomena, Americans are driving less and traffic is easing up, a growing number of studies show.

According to the Federal Highway Administration's "2011 Urban Congestion Trends" report, there was a 1.2 percent decline in vehicle miles traveled (VMT) last year compared with 2010. The drop follows years of stagnant growth in vehicle travel following a peak in 2007, before the economic downturn.

"Traffic really is as much a reflection of a given urban environment as it is the health of our economy," said Jim Bak, director of community relations at the transportation research firm INRIX, which found that traffic congestion in the United States fell by 27 percent last year.

"The interesting thing about it is if you're out there and stuck in traffic every day, it's probably a good sign that our economy is humming along," he said. "But when the economy is down, and if you're fortunate enough to have a job, you'll have a little better commute but your retirement fund probably isn't doing so well."

Using government research and data collected electronically from more than 100 million U.S. vehicles, INRIX found that congestion intensity has been steadily declining nearly every month from January 2010 through May 2012.

For Californians, avoiding traffic is a favorite pastime

But it is not as though the roads to the lake house will be empty this Fourth of July week, or thereafter. Indeed, Americans are still driving close to record highs. Commuters on the busiest stretches of highway in Los Angeles, for instance, still spend more than 60 hours in traffic per year.

"I find it's one of my favorite pastimes to try and find out where the traffic is and how to avoid it," said Cristina Romero, a case worker for Rep. Henry Waxman (D-Calif.), who drives an hour and 20 minutes each day from Pasadena, Calif., to her office in West Hollywood. Once, with no traffic, she completed the trip in 35 minutes.

But Romero admits that while the traffic in Los Angeles is terrible, over the 11 years she's lived in the area, traffic levels have been about the same. "I don't think it's increased, but I don't think it's decreased, either," she said.

Her observation is true for the entire country. Rather than maintain the 50-year legacy of a 2 to 4 percent increase in vehicle travel each year, the annual number of VMT in the United States has stalled and even gone into reverse. The total number of miles driven in the United States today is the same as in 2004.

Less driving means less global warming pollution and improved public health, but it may also signal a struggling economy.

Unemployment reached a high of 10.2 percent in October 2009 and was still hovering at 8.2 percent last May. With so many Americans still out of work, fewer people are getting in their cars to go do and buy things. That, in turn, means there's less need to drive goods and services around.

High fuel prices this year have also contributed to fewer VMT. Gasoline costs upward of $4 per gallon in many parts of the United States this spring, and although prices have inched down, many Americans are still choosing to drive less to save a few dollars, said Bak.

Don't drop by; just text me

But in some ways, the recent decline in VMT seems counterintuitive. The U.S. economy is slowly rebounding, and the population continues to grow while people are also driving until later in life, theoretically adding more trucks and passenger cars to the road. So is there more to this trend than economics?

The interesting thing for Roy Kienitz, transportation infrastructure consultant and former undersecretary for policy at the Department of Transportation, is that American drivers actually started changing their individual driving habits years before the recession started.

The overall number of miles traveled by road peaked just before the market collapsed, but the number of VMT per capita peaked in 2004 and declined over the next eight years until today, according to Kienitz's research, which is based on publicly available data.

Last year, the U.S. economy continued on a modest upward trend, reaching 3 percent growth in the last quarter. Yet 2011 was one of the steepest years in VMT decline. "This tells me that this is something that's speeding up, not slowing down," said Kienitz.

But, he added, "I think it would be too much to say we understand everything that's going on here."

The population shift toward urban centers and the rise in electronic communication are other possible reasons for reduced vehicle use. Living in a city makes bicycling and public transit more convenient, and the widespread use of cellphones and Web-based calling services like Skype may be making in-person visits less of a priority, especially among youths.

"Virtual contact through electronic means reduces the need for actual contact among young people," said Michael Sivak, research professor at the University of Michigan Transportation Research Institute. "Furthermore, some young people feel that driving interferes with texting."

The cha-ching factor

Sivak was lead author on a study published earlier this year, which examined the reduced rate of young people getting driver's licenses. Among the 15 economically advanced countries he analyzed, he found that places with a higher number of Internet users correlated with lower licensure rates among youths between 20 and 24 years of age -- including in the United States.

The initial expense of a car and the cost of insurance were also identified as reasons why young people were less likely to get a license.

This finding is bolstered by ongoing research by Ray Bingham, research professor in psychiatry at the University of Michigan, who also works at the Transportation Research Institute. In a survey of 160 teens and parents in the Midwest, he found that cost was the No. 1 reason youths weren't getting their licenses and starting to drive.

But as employment increases among youths and in the broader population, cost-related barriers linked to car use could disappear and driving rates could spike to all-time highs. The Federal Highway Administration predicts that the total number of VMT in the United States will go up again once the economy makes a stronger recovery.

According to the "2011 Urban Congestion Trends" report, "This unique timing makes the implementation of time-saving traffic operations strategies all the more important."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500