As oil brokers and analysts looked to Iran this week, Shawn Withee kept his eye on the competition around the corner.

As a manager at the ScrubaDub car wash and gas station near the Maine Mall in South Portland, part of Withee’s job is checking the prices of nearby gas stations, making sure his station stays competitive. Tuesday afternoon, his shop was selling a gallon of regular for $3.15, or $3.05 with a membership.

“We always try to keep it within a few cents of each other,” Withee said. “We’ve done like three surveys today to check everybody.”

In Maine and across the country, gas prices have shot up following attacks on Iran by Israel and the United States.

As the conflict spills out into the broader region, Iran has effectively closed the Strait of Hormuz, through which about 20% of the world’s oil is shipped, the Associated Press reported. On Tuesday, President Donald Trump said the U.S. military could escort oil tankers through the strait, which could help get things moving again.

Maine Sen. Angus King said the status of Hormuz is a “major concern” on a call with reporters Tuesday. He noted that oil prices had already risen sharply since last week.

The war and shipping route’s closure have rattled markets and, overnight Monday to Tuesday, led to the biggest single-day hike in the average cost of gas in years.

Withee’s prices have inched up, and they probably aren’t done rising.

In Maine, the average price per gallon for regular gas rose 8 cents from Monday to Tuesday, according to data aggregated by AAA. By Wednesday morning, the average cost had gone up another 10 cents, charting $3.09. That’s a 6% increase in two days.

Diesel rose about 13 cents over that same two-day period, while mid-grade and premium gas each went up about 17 cents per gallon.

All four categories AAA tracks in Maine were a few cents higher Wednesday morning than they were a year prior.

CONSUMERS FEELING IT

Drivers who pulled into stations from South Portland to Saco on Tuesday afternoon said they noticed right away. While some said the cost of gas bears little weight on their day-to-day, others said budgets — already tightened by rising food, rent and home energy costs — could hardly absorb another price hike.

Chelsea Withee, Shawn Withee’s wife, said she budgets about $20 a day for gas to fuel her commute from Windham to South Portland.

“It’s just been steadily increasing, and you can only get so far on a gallon,” she said. “I have to factor in my gas in my paycheck — like ‘Alright, we’ve got to make sure we have $100 for gas for the week,’ and that’s a big chunk of a check.”

Other drivers said they keep tabs on the various stations along their commute, seeking out the best deal between towns.

Standing under the canopy of a Mobil station in Scarborough, Old Orchard Beach resident Jenn Will said she noticed gas prices tick up about a dime Tuesday.

“Not surprising at all,” Will said. “With world events going on, it makes sense that (gas) would be going up.”

Will has a Sam’s Club membership, and she generally aims to fill up at the bulk retailer, where gas is typically cheaper. But that means planning ahead and, at times, partially filling the tank to make sure she can make the trip.

At another Mobil a few miles down Route 1, Saco resident Meaghan Brown topped off her tank for just under $30.

The station, a few blocks from Saco’s downtown, bustled during the Tuesday evening rush. A gallon of regular went for $3.05, or $2.95 if using the company’s credit card.

Brown said she’s “not really tracking” the cost of gas, but said that station always seemed to have the best deal.

One block over, a competitor station’s sign read $3.19 for a gallon of regular. That lot appeared empty.

Staff Writer Billy Kobin contributed to this story.