The average pump price of gasoline nationwide, including all grades and taxes, was $1.095 per gallon Friday, according to the Lundberg Survey of 10,000 stations.
That was down 1.24 cents from Aug. 7, Trilby Lundberg said on Sunday.
In about a third of U.S. cities surveyed, the price of self-serve regular gas, the type most used, had dropped to under $1 per gallon, she added.
At self-service pumps, the average price for regular gasoline was $1.037 per gallon, mid-grade was $1.144 and premium was $1.228.
At full-service pumps, regular was $1.473, mid-grade was $1.56 and premium was $1.635.
Prices have been falling all year, except for a brief jump beginning in late March that ended in early June.
While the U.S. bombing of suspected terrorist targets in Sudan and Afghanistan might have worried the crude oil market, it had little impact on actual prices.
"The immediate impact late last week was a very, very tiny blip in futures crude markets. So there is not at the moment any reason to predict a problem of price hikes," Lundberg said.