Gas prices across the US have fallen below $4 a gallon for the first time in more than five months.

The national average price for regular gasoline dropped to $3.999 per gallon Thursday, according to the American Automobile Association, down nearly 3 cents from the previous day.

The drop in gas prices comes as the Strait of Hormuz is set to reopen under a memorandum of understanding between the US and Iran aimed at ending the conflict that disrupted global oil supplies.

Gas prices across the US have fallen below $4 a gallon for the first time since March 30. Getty Images

It marks the first time the US national average gas price has fallen below $4 since March 30.

GasBuddy reported the national average at about $3.98 early Thursday after prices dipped below the $4 mark on Sunday.

Indiana has the lowest statewide average at $3.40 a gallon and is among 28 states where average gas prices are now below $4.

President Trump signed the US-Iran memorandum of understanding on Wednesday over dinner at the Palace of Versailles in France.

Iran’s closure of the key shipping route in late February cut off roughly 20% of the world’s oil supply, sending crude oil and gasoline prices sharply higher.

Global oil supplies were disrupted by the US-Iran conflict as shipments through the Strait of Hormuz were blocked. AP Photo/Richard Drew

Gas prices climbed above $4 nationwide in late March after most shipping through the strait was blocked.

The national average peaked at $4.56 a gallon on May 21 before beginning a steady decline as expectations grew that negotiations would lead to the waterway reopening.

Americans have spent about $46 billion more on gasoline since the start of the conflict, Patrick De Haan, GasBuddy’s head of petroleum analysis, said earlier this week, according to Reuters.