American drivers haven’t seen gas prices this high in more than three years.

The average price of a gallon of regular fuel is now over $4, according to motor club AAA. The milestone is a significant one, as it’s the first time gas prices have surged past $4 since August 2022. Just over one month ago, prices were $2.98, AAA noted.

Prices for fuel have skyrocketed in concert with oil prices that shot up after the United States launched an attack on Iran on February 28.

In response to the soaring prices, the Trump administration announced in late March that it would try to ease the pain at the pump by suspending air-pollution regulations for higher-ethanol E10 and E15 gas from May 1 to May 20.

The move is meant to bring more fuel to the U.S. market in a time when Iran’s presence in the Strait of Hormuz is slowing oil shipping. The waterway typically sees 20 percent of the world’s oil supply sail through it each year.

“Increasing ethanol content will generally increase our fuel supply, as the same amount of petroleum blendstock can be used to produce a greater volume of fuel,” said Jim Stanley, director of media relations at industry representative Western States Petroleum Association.

Falling prices can’t come any sooner for Americans across the country. In Oklahoma, which consistently has the nation’s lowest gas prices, a gallon of gas is up 82 cents compared to a month ago.

Amid the higher prices, Oklahoma remains the cheapest state for gas, followed by Kansas, Iowa, Nebraska, Arkansas, according to a statement from AAA released Thursday.

California, the most expensive state for gas in the country, saw its prices rise $1.19 since late February to $5.83 by late March.

Drivers in El Centro, a small city two hours east of San Diego, were already paying $1.32 more than they did a month ago. Gasoline is over $6 a gallon in two cities – San Rafael and Santa Rosa, according to AAA.

After California, Hawaii , Washington, Nevada and Oregon are the next four most expensive states, AAA noted.

Consumers looking to save money on fuel costs should fill up on Sundays, according to an analysis by fuel savings platform GasBuddy. Wednesday through Friday are the days when gas is most expensive, on average.

“While price trends fluctuate with oil markets and seasonal demand, weekly patterns remain surprisingly consistent,” GasBuddy noted. “In most states, prices gradually rise through the week before easing into the weekend, creating a reliable window for motorists to save simply by adjusting the timing of their fill-up.”