Kate Darby knows the price of gas has jumped about 15 cents in the past week.

But as the Mount Pleasant resident filled up her Dodge SUV on Tuesday afternoon at the Calhoun Street BP station near the funeral home where she works, Darby, 45, accepted such fuel fluctuations as a part of everyday life.

"I've noticed and we talked about it, but I still have to buy gas," she said.

From Mount Pleasant to James Island, that's how a lot of people felt Tuesday as the average price of a gallon of regular gas in the Charleston-North Charleston area went from almost $3.11 a week ago to more than $3.25, according to the American Automobile Association's Daily Fuel Gauge Report.

Over the same period, the state average jumped about the same amount -- from $3.09 to $3.22 -- and the national average increased from about $3.28 to about $3.37, according to AAA.

Driving the uptick are Iran's recent "saber-rattling," that is, conducting military exercises and threatening to cut off tanker traffic in the Straits of Hormuz; crude oil prices above $100 per barrel; and the expiration of a 45-cent per gallon ethanol tax credit, a AAA spokesman said Tuesday.

"Those three things are keeping that price high," said Tom Crosby, vice president of communications for AAA Carolinas. "The only thing that's depressing prices somewhat is the fact that our demand has dropped somewhat, 3 percent this year over last year."

Relative to the rest of the United States, consumers in South Carolina are in better shape because it gets more than 80 percent of its fuel from the Gulf of Mexico and because the state gas tax is lower than in most states, Crosby said.

On the other hand, the end of the corn-based fuel subsidy on Dec. 31 "hit South Carolina pretty hard because so many of the pumps use ethanol," he said.

Prices have gone up steadily on a year-over-year basis in the past decade, with the exceptions of 2002 and 2009, and some consumers have responded by driving hybrid cars, carpooling or combining trips.

Crosby hesitated to predict how much gas will cost next week or next year.

"It's just so hard to tell because if the economy starts doing well, the prices at the pump will do well," Crosby said. "If something really erupts … in the Middle East, then prices will go sky high. If we continue to drive less … then I think that's a damper on prices."

"If you and I could predict those types of things, we'd be really rich," he said.

On Tuesday, William Mallory, a 77-year-old retired insurance agent visiting from Georgia, blamed the oil companies. David Taylor, 65, a Meals on Wheels deliveryman from Charleston, blamed the Republicans. But most people, like Darby, seemed resigned to high gas prices as "part of reality."

"As it inches toward four dollars ... that's the panic point," Darby said.

Reach Brendan Kearney at 937-5906 and follow him at twitter.com/kearney_brendan.