"This has been a true price crash," said Trilby Lundberg, publisher of the Lundberg Survey.
The average price of a gallon of regular gasoline is $3.38, down nearly a dime over the past three weeks, Lundberg said.
"This crash began back when refining problems around the country were being fixed, one after the other, at the same time that our seasonal gasoline demand was shrinking," she said.
Crude oil prices have also dropped after having risen steadily.
Prices at the pump should drop even more in the coming days, as refiners cut how much they're charging distributors and retailers, Lundberg said.