American motorists, paying record prices for gasoline and concerned about the economy, drove less in May for a seventh consecutive month, pointing toward the first annual drop in driving since 1980, according to federal figures released yesterday.

"Four dollars per gallon may have been the trigger point we've been looking for," said Kenneth McGill, managing director for travel and tourism at consulting firm Global Insight Inc., of Lexington, Mass. "It's interesting to see Americans finally reacting to the price of gasoline by rationing consumption."

Americans drove 9.6 billion fewer miles in May 2008 than in May 2007, the third-largest monthly drop in the 66 years the data has been collected, the Federal Highway Administration said in yesterday's report. The decline amounted to 3.7 percent from May last year.

The May decline continues a seven-month decrease in driving that has amounted to 40.5 billion fewer miles traveled since November 2007, compared with the same period a year earlier. The seven-month slide is the longest streak since 1979, agency spokesman Doug Hecox said.

May's drop comes during a month that traffic usually rises because of the Memorial Day holiday and the start of the summer-vacation season.

Motorists cut back as the average U.S. retail gasoline price reached a then-record of $3.98 a gallon May 31. Rising fuel prices and a weak economy also marked the drop in driving in 1980, after the Soviet Union invaded Afghanistan and U.S. Embassy personnel in Iran were taken hostage.

In Pennsylvania, motorists drove 8.9 billion miles in May, or 4.3 percent less than the year before, the federal report showed. The drop in New Jersey was 5.2 percent to 6.1 billion miles driven.

Besides cutting back on driving, motorists increasingly are using fuel-efficient vehicles, carpooling, and taking mass transportation.

The combination means the federal highway trust fund - which relies on per-gallon taxes that do not rise with price - faces a multibillion-dollar shortfall next year, down from a surplus of more than $10 billion just three years ago.

Transportation Secretary Mary E. Peters said in a statement yesterday that the drop in driving miles demonstrated that the federal gasoline tax no longer was sufficient to finance the nation's transportation infrastructure.

The highway trust fund gets 18.4 cents per gallon from gasoline sales and 24.4 cents per gallon for diesel sales. Driving fewer miles and using more fuel-efficient vehicles means less gasoline consumption - and less funding for the trust fund.

"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," Peters said.

Last week, the House approved by a veto-proof margin an $8 billion infusion into the highway trust fund for the fiscal year beginning in October.

Slowing Down

Percentage drop in miles driven on all U.S. roads in May 2008 from May 2007.

Region % change

North Central -4.5

Northeast -4.2

South Atlantic -4.1

U.S. -3.7

South Gulf -3.2

West -2.3

SOURCE: Federal Highway Administration