PORTLAND – Gasoline prices hit a record high for the fourth straight day Tuesday with prices just shy of $2.50 a gallon in Maine, which boasted the dubious distinction of having the region’s highest gas prices.

The average price for regular unleaded was 3 cents a gallon higher than on Monday and a dime higher than Friday in Maine, according to AAA, which tracks gasoline prices nationwide.

The sharp rise can be blamed on worries about oil supplies from the Middle East, along with reduced refinery capacity due to a refinery fire in Philadelphia last week, said Matthew McKenzie, public affairs of director of AAA-Northern New England.

But even with prices that are more than 50 cents higher than a year ago, people don’t seem to be altering their driving habits much, McKenzie said.

“I think it’ll have to be over $3 a gallon for people to modify their driving patterns,” he said.

Nationally, gasoline prices rose Tuesday to a new high of more than $2.52 a gallon, according to AAA’s gasoline survey of 60,000 self-serve stations. That’s 20 cents higher than a month ago and 67 cents higher than a year ago.

In northern New England, the average gasoline price was $2.49 a gallon in Maine, $2.48 in New Hampshire and $2.44 in Vermont.

McKenzie said he’s not convinced Americans are willing to change their driving styles. America’s top three automakers reported record vehicle sales in July, with the bulk being full-sized pickup trucks and sport utility vehicles, he said.

“It tells me people want a larger vehicle, they want the utility that they bring and are willing to pay the price of poor fuel mileage,” he said.

Diesel fuel also reached a record high on Tuesday.

Diesel now averages about $2.56 a gallon in Maine, which was 3 cents higher than Monday and 66 cents higher than a year ago.