Updated

The average retail price of a gallon of gasoline in the United States plunged more than 25 cents in the past two weeks, as refining capacity was restored and demand slowed, a survey showed on Sunday.

The national average for self-serve, regular unleaded gasoline was $2.6587 a gallon on October 21, down about 25.3 cents per gallon from October 7, according to the nationwide Lundberg survey (search) of about 6,000 gas stations.

"This is the biggest drop in a two week period that we have ever seen in our many decades surveying the gasoline market, survey editor Trilby Lundberg said.

Supply is up due to restoration of refining capacity, which was damaged during Hurricanes Katrina and Rita, Lundberg told Reuters.

Demand was dampened as consumers cut back on gasoline consumption in response to skyrocketing prices, as well as by evacuations of areas such as the Gulf Coast (search).

Of the areas surveyed, Honolulu (search) had the highest average price at $3.03 a gallon for self-serve, regular unleaded gas on October 21, while the lowest average price was $2.20 a gallon in Tulsa, Oklahoma.

Preliminary data shows gasoline demand is 2 percent to 3 percent lower than a year ago, Lundberg said.

The current U.S. average price for a gallon of gasoline is just 3 cents above the pre-Katrina price, Lundberg said.

"It's been a real roller coaster since then," she said.

Lundberg said Hurricane Wilma (search), which is bearing down on Florida after hitting Mexico, seems to be benign to gas supply, but not to gasoline demand. "The evacuations do remove some demand."