The weighted average price for all three grades declined to $2.45 a gallon on Friday, said Trilby Lundberg, who publishes the semimonthly Lundberg Survey of 7,000 gas stations around the country.
"Self-serve regular, the biggest seller, averages $2.43 per gallon," Lundberg told CBS Radio News. The price for midgrade was $2.53, while premium-grade hit $2.63.
"The lowest self-serve regular average in our survey is Tulsa at $2.06, and the highest is Miami at $2.74," she said.
The average pump price for all three grades on Aug. 29, the day Katrina made landfall on the Gulf Coast, was $2.65, according to the survey.
"The price is down 23 cents per gallon from two weeks ago, and it is also down nearly 49 cents in the past month," Lundberg said.
"It's a comeback in supply. First of all, our refinery damage in the Gulf from those two hurricanes is coming back, and in addition, a lot of gasoline imports rushed in to fulfill the differences between demand and our domestic refining capacity," she said.
And prices could continue to fall, "but not at the same rate, because demand will not be shrinking, as it did with such high prices, and because most of our refineries are back on stream."