BANGOR – Gasoline prices shot up about 10 cents a gallon Friday in what’s being called the biggest one-day increase in recent state history.

Friday’s jump is in addition to a 10 cent piecemeal increase during the last week, and, before that, a 19 cent increase since last year.

From energy analysts who make a living studying the petroleum markets to consumers who earn a living just to pay the prices at the pump, no one on Friday could figure out why the dramatic increase occurred. Speculation covered the gamut – from retailers allegedly upping the price to capture dollars from visitors to the National Folk Festival or tourists coming to the state for the last week of summer vacation, to price gouging by big oil companies.

What’s true and what’s not is anyone’s guess, according to observers, but opinions are plentiful and they cost nothing.

“I’ve never seen it go up 10 cents overnight unless there was a tax increase,” said Larry Burke, owner of Burke’s Exxon in Brewer. “And from what I’m hearing, it’s going to go up even more. That’s the word on the street. But I’m not ready to go buy a horse just yet.”

In a survey of gasoline prices throughout the region Friday by Bangor Daily News reporters, the lowest price for regular gasoline was $1.599 early Friday at a convenience store a half-mile from the National Folk Festival site in Bangor. But that low price didn’t last long. Shortly after noon, after a shipment was delivered along with an invoice, the price went up 10 cents a gallon.

The highest price for a gallon of regular unleaded gas was $1.799 at stations in Belfast and Caribou.

Burke said he spent Friday morning “pounding the phones,” trying to get an explanation from wholesalers as to why the price jumped so much in less than 24 hours. And an executive vice president for one wholesaler, R.H. Foster Energy LLC, said he was burning the phone lines trying to find out why from his suppliers, Chevron, Exxon Mobil, Gulf and Texaco.

“Nobody’s talking,” Robert Tracy, executive vice president for R.H. Foster, said Friday morning. “I have no official word. The people who do this for a business are horrified, absolutely horrified.”

An industry analyst based in Washington, D.C., said she could not explain why Maine experienced such a dramatic increase in fuel prices in less than 24 hours.

“That’s an awful lot in one day,” said Rayola Dougher, a senior policy analyst with the American Petroleum Institute. “Why you were hit all of a sudden in a 24-hour period, I really can’t say.”

But, she added, “it really doesn’t surprise me.”

Dougher said one explanation for the price jump may have been a similar-size price increase on gasoline futures that occurred Thursday on the New York Mercantile Exchange. Traders upped the price of gasoline futures by 9.6 cents a gallon for deliveries to be made in September.

“September’s next week,” she said. “A number of contracts are tied to what happens in NYMEX.”

Dougher said traders may have grown impatient with international concerns and decided to react. She said the continuation of the Iraq war, delays in bringing Iraq online to export crude, vandalism to a major pipeline in Iraq last week, and fighting in other parts of the Middle East have contributed to a decline in exportable crude.

In the United States, gasoline inventories are well below what they should be, said Michael Shea, president of Webber Energy Fuels in Bangor.

“There’s increased pressure on prices because inventories aren’t looking as fast as they should be during the summertime,” he said. “This is nationwide. This isn’t just Bangor.”

Maine wholesalers such as R.H. Foster and Webber get their gasoline from refineries near Philadelphia, in New Jersey, New Brunswick and the Gulf Coast. The electricity blackout last week shut down refineries in New Jersey, the Midwest and parts of Canada, but not in New Brunswick. While the U.S. refineries returned to production shortly after power was restored, it took longer for the Canadian facilities to fire up.

“At this point, the market is so sensitive that every disruption is having an impact because there’s no extra product on the market,” Michelle Firmbach, a Portsmouth-based spokeswoman for Irving Oil, said Friday. “Gasoline inventories are at the lowest levels in six years.”

Firmbach said she could not say whether Irving’s inventories were running low, but added that the company is affected by worldwide market conditions.

Since the start of the summer, the price of crude has gone from $25 a barrel to $32 a barrel, with a $1 increase Thursday. Many area retailers on Friday said they’ve tried to hold down their prices in the last two weeks even though invoices were arriving with higher wholesale prices.

“All week long it’s been going up but everyone was toeing the line,” Burke said. “They couldn’t do it anymore.”

Now retailers are bracing for more price increases in the coming days, and consumers should be, too.

In Belfast, Clint Duval, owner of Duval Auto Service, said the price spikes “suck.” He said he was notified by fax from his wholesaler Thursday evening that his price was going up 7 cents per gallon across the board; when he came to work Friday, another fax was waiting to inform him gas had gone up another 13 cents. On Friday, Duval was selling regular for $1.739.

Duval said he also was notified that his next shipment would cost 20 to 21 cents per gallon more, meaning that gas prices in Belfast should break the $2-per-gallon mark within the next few days.

“You know what I think? I think [President] Bush and [Vice President] Cheney are lining their pockets,” Duval said. “I don’t know why [the prices] keep going up, it just doesn’t make any sense. If I had a crystal ball, I’d tell you.”

Robert Duke, operations manager for Maritime Farm Stores, located in towns from Damariscotta to Belfast, said Friday that another price increase was on its way by nightfall. Duke was selling regular for $1.759 on Friday.

“Things have been climbing,” he said. “When prices go up, we always lose, too.”

In Aroostook County, regular unleaded gasoline was selling for $1.799 in Caribou, Limestone and Presque Isle. Since the Phish concert earlier this month in Limestone, which drew more than 60,000 people, the price of gasoline has increased by 14 cents.

Gas prices at Carroll’s IGA in Trenton, reportedly among the lowest in Hancock County on any given day, increased 8 cents on Friday alone, owner Carroll Leland of Bar Harbor said as motorists jammed the gas lanes to tank up at $1.68 a gallon for regular.

“We can’t blame [the rising prices] on the war, I don’t think,” said Leland, who intentionally takes a lower profit on gas as a way to draw people into his Route 3 store.

Jed Patterson of Ellsworth, who stopped at Carroll’s for lunch, wasn’t surprised that prices were rising, but he was suspicious.

“It just seems there’s got to be something fishy with the gas companies in Ellsworth,” he said. “We always have the highest gas prices in the state.”

In Rockland, Kevin Widell, manager of the Park Street Puffin Stop, was asked if he had gotten many customer complaints. He said, “Just from me. I travel 35 to 40 miles to work.”

Not many people were filling their cars at gas stations on Broadway in Bangor on Friday afternoon, where gas prices were $1.779 for regular, the highest price in the area.

Kathy Laforest of Hudson pulled up to the Texaco station on Broadway and got sticker shock.

“I wished I’d looked before I chose premium [at $1.879],” she said. “Oh well. You gotta do what you gotta do.”

Across the street at the Mobil station, Ben Lam of Brewer was putting gas in his Honda.

“Super is what I use, and $1.97 is pretty high. It better be worth it for that price.”

In Belfast, lawyer Joe Baiungo is taking a more philosophical approach to the price increases.

“It doesn’t matter what they charge, we still need to buy it,” he said. “At least it’s not as high as bottled water.”

Baiungo was misinformed on that one, however, as a gallon of Poland Springs water was selling for $1.39 at the Main Street Market.

NEWS reporters Liz Chapman, Amanda Dumond, Walter Griffin, Nancy Jacobson and Leanne Robicheau contributed to this report.