The US on Monday is recording average petrol prices slightly above $4, a level not seen since March, data from national gasoline trackers from the American Automobile Association and fuel savings website GasBuddy show.
"Gas prices are now down by more than 90 cents a gallon. That’s over seven straight weeks of prices declining," US President Joe Biden tweeted on Saturday.
Americans have been struggling with high petrol costs in a summer snarled with high demand for travel after two pandemic summers and record levels of inflation affecting costs elsewhere.
Russia's invasion of Ukraine in February put pressure on limited global petrol supply, when sanctions on the major oil producer from the US and other Western countries led to a steep rise in prices.
The US reported a record $5 average for petrol prices in June, and prices at the pump have been on a steady decline since.
GasBuddy's national tracker on Monday shows at least 25 states have reported average gas prices dip under $4.
The AAA reports that fewer Americans have been heading to the pump in the last week and predicts continued price decreases.
"It’s possible that the national average will fall below $4 this week," AAA spokesman Andrew Gross said.
It poses a political win for Mr Biden, challenged by Republicans upset about high fuel costs — even though the president does not have much control over gas prices as state taxes heavily affect local pricing. Mr Biden has released oil from the US national reserve and spoken to refiners on increasing production.
The lower prices also help Democrats in trying to hold on to Congressional legislative powers during midterm elections this November.