US drove 9.6bn fewer miles

The figure represents the largest year-on-year decrease for May since the Federal Highway Administration (FHA) began compiling statistics 66 years ago, the agency said.

"This is the largest drop in vehicle miles travelled for any May, which typically reflects increased traffic due to Memorial Day vacations and the beginning of summer," the FHA said in a statement.

Rising gasoline prices have pushed people in the US out of their cars and into public transportation or carpools, officials said.

"High fuel prices are behind the fall in vehicle miles traveled," FHA transportation specialist Steven Jessberger told AFP.

"A number of public transportation authorities are reporting an increase in ridership compared with last year. The service I use has seen an 18% increase in ridership compared with a year ago," said Jessberger, who commutes 50 miles daily by bus into Washington.

In the first five months of this year, Americans put in nearly 30bn fewer miles on public roads than in the same period in 2007, the data showed.

During that period, gasoline prices rose from about $3.20 a gallon to more than $4.

Vehicle miles traveled in May this year were at their lowest level since 2003, FHA data showed.

In May 2003, petrol averaged around $1.70 a gallon in the United States.

By May 2007, it had doubled to around $3.40, and a year later it was nudging four dollars per gallon, according to data from the US Energy Information Administration.

- Dow Jones