Gas prices back up a dime

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(CNN) -- After a lull toward the end of 2007, gas prices shot back up nearly ten cents a gallon over the past three weeks, crossing the $3 mark again, according to a survey published Sunday.

The average price of a gallon of self-serve regular is $3.07, the Lundberg survey found. That's 75 cents higher than the price a year ago.

Gas prices were catching up to recent increases in the cost of crude oil, publisher Trilby Lundberg said. Also, retailers and refiners have increased their profit margins slightly, she said.

The survey looked at the prices at thousands of gas stations nationwide on Friday.

Lundberg said she does not expect gas prices to rise much in the next couple of weeks if crude oil prices remain steady.

"Significant hikes at the pump are not likely until seasonal demand comes out of its winter lull about a month from now," when people start driving more, she said.

The lowest average price for a gallon of self-serve regular was in Cheyenne, Wyo., at $2.77. The highest was in San Francisco, at $3.39

Here are the prices in some other cities (beginning with three that have upcoming presidential nominating contests):

Detroit - $3.05

Charleston, S.C. - $2.94

Reno, Nev. - $3.14

Jackson, Miss. - $2.95

Portland, Ore. - $3.04

Miami - $3.17

Boston - $3.08