Your summer ride might be a little more joyful now that gas prices may have already peaked for the year.

As the Memorial Day weekend kicks off the summer travel season, American motorists are poised to benefit from declining gas prices.

While gas remains expensive in certain pockets, including $4-per-gallon California, the national average is falling.

The national average is unlikely to hit $3 per gallon for the fifth straight calendar year, said Patrick DeHaan, head of petroleum analysis at fuel-savings app GasBuddy.

"It’s another great year to hit the road," he said. "Gas prices remain affordable in most areas, unless you’re in California."

Jeannie Crawford knows that first hand.

The former retail store manager recently moved with her family from California to South Carolina. Her new state's vastly lower gas prices – $2.48 compared with $4.03 as of Thursday, according to AAA – were a nice welcome gift.

Crawford, her husband, and her son drive three vehicles – a 2012 Kia Rio, a 2005 Ford Explorer Sport Trac pickup and a 2012 Nissan Versa – for a total of about 250 miles per week.

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"I think the prices here in SC are as they should be all over the country, and think there isn't any excuse for such a price difference," she said in an email.

South Carolina was the fourth-cheapest state to fill up as of Thursday, according to AAA.

The national average on Thursday was $2.85, down 1 cent from a week ago and down from $2.89 in early May, AAA spokesperson Jeanette Casselano said.

"There’s a large possibility we may have already peaked," she said.

Last May, prices peaked at $2.97. "People are excited because they’re saving a little bit of money compared to last year," Casselano said.

AAA projected that 37.6 million Americans would travel by car for Memorial Day weekend, up 3.5% from last year and representing the second-most ever, trailing only 2005.

GasBuddy projected that Americans would spend $107 billion on gas from June through August, slightly higher than last year due to the additional travelers.

"People are feeling really good about the economy," DeHaan said. "That's probably why motorists have such an appetite to hit the road this summer."

Still, there are several unknowns that could affect gas prices, he said.

As hurricane season approaches, any effect on Gulf Coast refinery production or shipping routes along the East Coast could limit production or supplies and thus increase prices.

Geopolitical factors are also difficult to predict. For example, the U.S.-China trade dispute and the Trump administration's tussle with Iran remain risks that could increase prices.

Here are the 10 cheapest states to fill up (as of Thursday), according to AAA:

Alabama: $2.45 Louisiana: $2.46 Mississippi: $2.46 South Carolina: $2.48 Arkansas: $2.50 Tennessee: $2.54 Missouri: $2.54 Texas: $2.56 Oklahoma: $2.57 Virginia: $2.58

Here are the 10 most expensive states to fill up (as of Thursday), according to AAA:

California: $4.03 Hawaii: $3.65 Washington state: $3.55 Nevada: $3.48 Alaska: $3.47 Oregon: $3.43 Idaho: $3.20 Utah: $3.19 Arizona: $3.15 Pennsylvania: $3.01

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.