Record gas price: Dirty dozen

NEW YORK (CNNMoney.com) -- Gas prices hit record highs for the 12th straight day Thursday, as drivers prepared to hit the road for the Memorial Day holiday and the start of the summer driving season.

There is no immediate relief in sight, as prices continue to rise in most of the country. Midwest prices continue to soar, resulting in the three most expensive states in the nation being in that region.

Gas prices have stayed above $3 a gallon longer than during any previous spike, and relief is nowhere in sight.

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The latest reading from AAA Wednesday showed that the nationwide average for a gallon of regular unleaded hit $3.227, up from $3.221 on Wednesday.

The motorist group's survey of 85,000 gas stations, by far the broadest sampling of gas prices, has been showing a series of record highs starting May 13.

The national average has now been above $3 a gallon since May 4. That's the longest stretch with prices above the $3 mark; a 19-day period was reached last August following Israel's invasion of Lebanon. That was the previous longest spike in gas prices.

The AAA national average now shows prices up 3.6 percent over the course of the last week, along with an increase of 13 percent during the last month.

And higher prices could be on the way during the crucial summer driving season.

AAA warned in congressional testimony last week that it believes prices will approach $3.25 a gallon over the next 60 days.

Even with the record prices, AAA is predicting a record number of Americans will be hitting the road during the holiday weekend, with 38.3 million expected to be traveling 100 miles or more, up 1.7 percent from a year ago. And most of those - 32.1 million - will be driving, according to the motorist group.

For the third straight day, New Jersey was the only state with an average price below the $3 threshold, but it continues to edge toward that benchmark. The average price in the Garden State rose to $2.954 from $2.95 on Wednesday.

New Jersey, which has a state gas tax of 14 cents, or about 7 cents less than the national average, got the distinction as the last state with gas below $3 on Tuesday when the average price in New Hampshire and South Carolina crossed the $3 mark for the first time.

Ironically, New Jersey is one of only two states - along with Oregon - where the law mandates full service at every pump.

The fastest-rising gas prices are now in the Midwest. Illinois retained the dubious distinction of the state with the most expensive average price, as the price reading there rose to $3.515 from $3.498 Wednesday.

Michigan saw prices up 1 percent to $3.508, keeping its ranking as having the nation's second-most expensive average price, while Indiana moved into No. 3, passing California, with a 1.4 percent jump in prices to $3.456.

For the second straight day, Ohio saw the biggest jump in prices, as the average price soared nearly 7 cents to $3.364 from $3.298 a gallon.

California, which had the highest price through last weekend, saw prices ease 0.7 cents to $3.435 , putting it No. 4 in prices. Prices also posted modest declines in Oregon and Washington.

There were a total of 20 states where prices declined in the latest reading, with the biggest drop being a 2.1 cent decline in Minnesota. But motorists there will probably be hard-pressed to notice any relief as the average price fell by less than a half cent in 11 of the states where prices slipped, and by a penny or less in three more states.

Different regions of the country have to comply with different formulations of gasoline during the summer months in an effort to control smog. That can cause regional spikes as the refineries cut back production of a certain blend due to change over to make the summer formulation, or due to unplanned shutdowns.

Recent problems at refineries helping to lift gas prices to record levels have included fires, power outages and longer-than-usual maintenance periods.

But there is typically a regional retreat in prices once production of the new blend picks up again.

Before this recent run of record-high gas prices, the highest price ever recorded in current dollars was $3.057 in the AAA survey, which was set Sept. 4 and Sept. 5, 2005, in the wake of Hurricane Katrina. That storm disrupted refinery operations and pipelines and caused a temporary spike, sending prices above the $3 mark for eight days.

The current price increases are due to problems in gasoline supplies and refinery output. The average gas price went above $3 a gallon on May 4 and has been climbing since.

While crude oil prices have fallen over the last few weeks and oil supplies are high in the United States, problems at several refineries have crimped gasoline output ahead of the summer driving season.