Gasoline prices hold steady

ATLANTA (CNN) -- U.S. retail gasoline prices remained nearly unchanged over the past two weeks as crude oil dipped and recovered during the same period, according to a new nationwide survey released Sunday.

The average price of self-serve regular was a fraction of a cent under $2.85 a gallon on April 23, said Trilby Lundberg, publisher of the Lundberg Survey. That's down less than half a penny from the previous survey, conducted April 9, and tracks the price of crude oil over the same period. The prices for both products "are virtually the same was they were on April 9," Lundberg said.

Crude dipped during that period in large part because of a volcanic eruption in Iceland, which resulted in a massive cloud of ash that shut down air travel across much of Europe. When traders saw that the resulting disruptions were easing, oil prices returned to nearly the same levels they held before the April 14 eruption, Lundberg said.

Summer vacation season is on the horizon for Americans. But with U.S. fuel stocks remaining high and about 15% of refinery capacity available that is not currently being used, Lundberg said increased demand is likely to put little upward pressure on prices at the pump without increases in the cost of crude.

"From here, any rises in the price of gasoline, at least short term, will probably be small," she said.

The highest average prices in the continental United States were in Chicago, where self-serve regular averaged $3.15 per gallon. The lowest were found in Tulsa, Okla., at $2.60.

A sampling of average prices in other cities: Atlanta, $2.75; Baltimore, $2.81; Denver, $2.67; Manchester, N.H., $2.75; Miami, $2.85; Milwaukee, $2.90; San Francisco, $3.09; Tucson, Ariz., $2.79