The U.S. average price of gasoline dropped 27 cents over the past three weeks, to $2.44 a gallon.
Industry analyst Trilby Lundberg said Sunday that the pump price fell even though crude oil prices gained strength, as gasoline supply outweighed demand.
Further price drops are likely if crude oil prices don't skyrocket, because the Sept. 15 change to winter grade gasoline comes with a cost cut in much of the country.
The cheapest price recorded in the continental United States was Charleston, South Carolina, at $1.94.
The highest was $3.31 a gallon in Los Angeles.
The national average price of diesel was down 9 cents over the past three weeks to $2.63 a gallon.