California’s state average for a gallon of gas has surged above $6, making fuel in the Golden State the most expensive across the U.S.

The average price at the pump in California hit a record $6.021 per gallon on Tuesday, according to AAA. Prices are up 31 cents over the last month, and $1.89 higher than a year ago.

California’s prices are the most extreme, but gas is rising across the country.

The national average hit a record $4.523 on Tuesday, with every state now averaging more than $4.

The sharp jump is in part thanks to a rise in oil prices, which makes up more than half of the ultimate price of gas.

“The high cost of oil, the key ingredient in gasoline, is driving these high pump prices for consumers,” Andrew Gross, AAA spokesperson, said Monday in a statement.

“Even the annual seasonal demand dip for gasoline during the lull between spring break and Memorial Day, which would normally help lower prices, is having no effect this year,” he added.

But oil is not the only factor that influences gas prices, and a lack of refining capacity is also pushing up prices.

Refiners turn oil into petroleum products like gas that we use daily. Demand for products is surging as economic activity returns, but refining capacity is lower than pre-pandemic levels, which is contributing to the rapid price rise.

Retail diesel prices are on the move, too, with the national average for a gallon hitting a record $5.573 on Tuesday. Prices are up $2.40 over the last year.