Motorists in California and other West Coast states have been hardest hit because of refinery explosions that have also cut into supplies.
Nationally, the average price of gasoline at the pump has risen more than 5 cents to $1.267 cents a gallon since early July, according to the California-based Lundberg Survey. In February, the average price dipped below $1.
Prices could continue upward during August as more Americans take to the road for vacations and weekend outings.
"You're right in the middle of the driving season and the economy is strong. People are driving around, taking vacations. There is more upward pressure," said Alvin Silber, an analyst with Herzog Heine Geduld.
Production cuts were announced by OPEC and other big oil producers in February. To the surprise of many analysts, OPEC countries have stuck to their quotas and a worldwide glut of crude oil that pushed prices down to historic lows during 1998 and early 1999 is disappearing.
At the same time, demand for both crude oil and refined gasoline is increasing, especially in Asia where countries are emerging from the economic crisis that began two years ago.
As a result, the price of key grades of crude oil worldwide has nearly doubled since the OPEC cuts went into effect, said Fadel Gheit, an analyst with Fahnestock & Co.
"OPEC's death has been greatly exaggerated in the last three or four years," Gheit said.
In California, an explosion forced Mobil Corp. to cut production at its Torrance refinery Wednesday. The company's Richmond plant was damaged in a July 10 blast and has not resumed full production.
Production is lagging at an Exxon refinery in Benicia and a Tosco plant in Avon has been shut down since March because of fires.
Even at today's prices, gas remains a bargain, Gheit said. When adjusted for inflation, prices are at their lowest level since World War II.