ATLANTA (CNN) -- Gas prices fell 10.72 cents over the past two weeks, to $2.78 per gallon of self-serve regular, according to a national survey.
That brings the total decrease to more than 28 cents per gallon over the four weeks ending Friday, said Trilby Lundberg, publisher of the Lundberg Survey, which tallies prices at about 5,000 gas stations.
Gas prices have slid more than 40 cents since May 18, when they peaked at $3.18 per gallon.
In the latest survey, St. Louis drivers paid the least, at $2.52 per gallon of self-serve regular, and Chicago drivers paid the most, at $3.15 per gallon.
Lundberg attributed recent price cuts to increased production by U.S. refineries after months of extended repairs made necessary by seasonal reformulation requirements, accidents and power outages.
In addition, crude oil prices have dropped and, to a lesser degree, the high prices of the last few weeks had depressed gasoline demand, she said.
But, she said, the drop may be over.
The unbranded wholesale price that independent marketers pay is up in a few parts of the country and the recent price cuts are likely to encourage consumers to drive more, increasing demand during the peak driving season, she said.
In addition, daylight-saving time has been extended until early November, which means drivers will have an extra hour of daylight in which to zoom around in their vehicles, she said.
Here are prices in some other cities:
-Baton Rouge, La.: $2.65
-Houston: $2.66
-Atlanta: $2.72
-Boston: $2.78
-Washington: $2.84
-Boise, Idaho: $2.94
-Los Angeles: $2.85 
