New federal data showing further steep declines in the number of miles Americans are driving is additional proof that the country needs new means—other than the gas tax—to finance the nation’s transportation infrastructure, according to U.S. Secretary of Transportation Mary E. Peters. "By driving less and using more fuel-efficient vehicles, Americans are showing us that the highways of tomorrow cannot be supported solely by the federal gas tax," Peters said. "We must embrace more sustainable funding sources for highways and bridges through more sustainable and effective ways such as congestion pricing and private activity bonds."

Americans drove 9.6 billion fewer vehicle-miles traveled (VMT) in May 2008 than in May 2007, according to the Federal Highway Administration (FHWA) data. This is the largest drop in VMT for any May, which typically reflects increased traffic because of Memorial Day vacations and the beginning of summer. It is the third-largest monthly drop in the 66 years such data have been recorded. Three of the largest single-month declines—each topping 9 billion miles—have occurred since December.

VMT on all public roads for May 2008 fell 3.7 percent compared with May 2007, marking 29.8 billion fewer miles traveled in the first five months of 2008 than in the same period a year earlier. This continues a seven-month trend that amounts to 40.5 billion fewer miles traveled between November 2007 and May 2008 than during the same period a year before.

As Americans drive less and rely increasingly on mass transit, carpooling, or other options, the federal Highway Trust Fund receives less revenue from gasoline and diesel taxes—18.4 cents per gallon and 24.4 cents per gallon, respectively.

"Less driving means less money for the Highway Trust Fund," said Acting Federal Highway Administrator Jim Ray. "The status quo cannot and will not work in the 21st century."

To review the FHWA’s Traffic Volume Trends reports for May 2008, visit www.fhwa.dot.gov/ohim/tvtw/tvtpage.htm.