CAMARILLO, Calif. (AP) _ Although oil prices have remained steady, the cost of gas jumped nearly 13 cents per gallon in the past two weeks, according to the Lundberg Survey.
San Francisco had the highest average price at $1.95 and Salt Lake City had the lowest at $1.43.
The average price of gas, including all grades and taxes, was $1.67 on Friday, up 12.69 cents, or 8.4 percent, from April 6, according to the survey of 8,000 stations nationwide.
It was the largest two-week jump in terms of cents per gallon since the survey began a half-century ago, analyst Trilby Lundberg said Sunday. She did not adjust the figures for inflation.
``This is purely a U.S. gasoline market phenomenon, not crude oil, not OPEC,'' Lundberg said. ``Crude oil prices are little changed for weeks now.''
Supplies are tight because environmental protection requirements that kick in for spring and summer are forcing more complicated and expensive refining as gasoline is reformulated to produce less smog.
Price hikes ranged from less than 7 cents per gallon for self-serve regular gas in the West - which already had the country's highest prices - to 23 cents in Chicago.
Sam Hussin, manager of a Shell station on Chicago's West Side, said prices also started rising around this time last summer, ``but not like this.''
``Last year two dollars was the max and now it's already over two dollars and the summer just started,'' Hussin said.
No hikes were reported for Honolulu; Anchorage, Alaska; Portland, Ore.; and Seattle, apparently because their supplies were not required to be reformulated.
Lundberg said she expected some markets will continue to see price increases. But she doubted that the overall average price will hit $2 per gallon ``in any foreseeable future.''
``The national average price is still a nickel under last June's peak and might never reach it,'' Lundberg said. ``Unless crude oil prices increase significantly or unless an emergency occurs affecting either pipelines or refineries, both gasoline price and supply should soon cease their extreme behavior.''