The national average price for a gallon of gasoline has increased a penny in the last week to $2.43 per gallon as refinery issues surfaced in the Great Lakes, fueling prices in several states to jump noticeably.

“The Great Lakes has seen a flurry of gas price increases over the last week as several refinery issues have surfaced, pulling the national average up nearly single-handedly,” said Patrick DeHaan, head of petroleum analysis for GasBuddy. “Without such ill-timed disruptions, we’d see a plentiful portion of falling pump prices, but now, the bitter taste of rising prices during the holiday lingers for many. But with the New Year set to roll in accompanied by a strong cold front, I’d expect gasoline demand to weaken, thus softening the outlook for gas prices in the weeks ahead and eventually delivering lower gas prices. Offering a brief glimpse into 2018: motorists won’t be loving what they see, but the devil’s in the details.” GasBuddy will be releasing its Annual Fuel Outlook for 2018 on January 3.

Roughly half of the nation’s 50 states saw average gasoline prices increase in the last week, with the Great Lakes leading the charge higher due to an outage at both ExxonMobil’s refinery outside Joliet, IL and Marathon Petroleum’s refinery in Robinson, IL. Outages generally last days or weeks, but some sources indicate ExxonMobil’s refinery may limp along for several months until previously scheduled maintenance in late-Winter and make repairs then.

Data from the Energy Information Administration last week showed a 1.2 million barrel increase in gasoline inventories, albeit much smaller than recent builds as demand for gasoline increased to 9.4 million barrels as millions of Americans finished their holiday gift purchasing. Refinery utilization increased as well to 94.1% of capacity while gasoline production dipped to 10.1 million barrels. Crude oil inventories, on the other hand, declined a sizable 6.5 million barrels. Such large declines are common toward the end of the year as oil companies draw down inventories for tax purposes.

Looking state-by-state, the largest changes in average gas prices were seen in: Indiana (+9 cents), Ohio (+8 cents), Illinois (+8 cents), New Mexico (-7 cents), Wisconsin (+6 cents), Michigan (+6 cents), Colorado (-5 cents), West Virginia (+5 cents), Kentucky (+5 cents) and Missouri (+4 cents).

States with the lowest average gasoline prices: Alabama ($2.15), Missouri ($2.17), Arkansas ($2.17), Oklahoma ($2.17), Mississippi ($2.18), South Carolina ($2.19), Texas ($2.20), Kansas ($2.21), Tennessee ($2.21) and Louisiana ($2.21).

States with the highest average gasoline prices: Hawaii ($3.29), Alaska ($3.10), California ($3.07), Washington ($2.88), Oregon ($2.73), Pennsylvania ($2.69), Nevada ($2.66), Connecticut ($2.64), New York ($2.63) and Montana ($2.59).