Gas Prices Rising About A Dime A Week

Gasoline prices have gone up an average of 20 cents per gallon nationwide in the past two weeks.

The retail price of self-serve regular gas rose to $2.55 cents per gallon, according to the latest Lundberg Survey released Sunday.

As of Friday, a gallon of midgrade gasoline averaged about $2.66, and premium cost nearly $2.76, according to the survey of 7,000 gas stations across the country.

"San Francisco has the highest average price, $3.10 per gallon, and the lowest is in Anchorage, at $2.22," publisher Trilby Lundberg told CBS News.

"This is not from crude oil. We have many refining projects, both planned and unplanned, that are reducing gasoline supply right now. We also have much stronger gasoline demand then usual," Lundberg said.

Fewer imports also have boosted oil and gasoline prices lately. On Wednesday, the government reported that total U.S. motor gasoline inventories fell by 3.8 million barrels to 216.4 million barrels, a sharper decline than the 1.4 million barrel drop that analysts had expected.

The rising prices are catching motorists between dueling demands, reports in Boston: The demand of getting to their jobs and the demand of paying for gas.

"In this country, we really live on the edge in terms of gasoline demand and the ability to produce sufficient quantities at times," Fimat USA energy analyst and senior vice president John Kilduff said last week on CBS News' The Early Show.

The bottleneck is in refining the oil into gasoline.

"This time of year, refiners go into a maintenance period where they rejigger their refineries to be able to emphasize gasoline production. What's happened, though, is we've been caught flat-footed. Several refineries, almost a refinery a day, has had some problem of some magnitude," Kilduff told co-anchor Harry Smith. "One refinery is completely off-line and other problems have cropped up to pinch supplies at the moment. We're only running at 58 percent of capacity at the moment."