US Driving in May drops 3.7%:

The 9.6 billion miles less traveled was the biggest drop ever for any May, when traffic usually increases due to the Memorial Day holiday and the beginning of summer vacations.

During the first five months of the year, highway travel was down 29.8 billion miles, or 2.4 percent, from the same period in 2007.

“The decline in American driving is deepening,” U.S. Transportation Secretary Mary Peters said.