Gas prices have plunged 27% as 43.2 million Americans hit the road for Fourth of July celebrations

Motorists will finally have some respite from sky-high gas prices this Fourth of July weekend after costs plummeted by 27 percent from last year.

A record-breaking 43.2 million Americans are set to travel by car this weekend - up 2.4 percent on last year - according to the American Automobile Association. 

At the same time gas prices have come tumbling down to $3.55 a gallon on Thursday, compared to $4.87 during the same period last year.

It marked a $1.33 - or 27 percent - drop in 12 months, according to the US Energy Information Administration (EIA).

It is the second-largest one-year decline in gas prices ahead of a July Fourth weekend since the EIA began tracking the data 33 year ago, Wells Fargo analyst John LaForge told CNN. 

The biggest drop occurred during the Great Recession when the cost per gallon fell by $1.45 - or 30 percent - between June 2008 and June 2009.

Meanwhile the price of diesel has fallen from $5.7 to $3.8 per gallon in the last 12 months. 

Motorists in Indiana have enjoyed the most significant decrease in costs this year, with the price of a gallon falling by $1.58 per gallon. 

Ohio, California and Illinois also saw declines of $1.48, $1.47 and $1.47 respectively.

However this year's decline is in part because gas prices reached such historic highs last year. 

The cost of filling up still remains well above 2020 and 2021 levels, according to EIA data.

Last summer, gas prices shot up to their highest level since the 2008 financial crisis, due to a nationwide heatwave which prompted Americans to crank up their air conditioning and put pressure on gas levels.

The US also experienced the 'trickle down' effect from soaring gas prices in Europe which were pushed up by Russia's invasion of Ukraine. 

Wholesale oil prices are now just starting to come down thanks to the Federal Reserve's interest rate hikes which have slowed the economy into recession. 

And the much-hyped fears of disruptions to Russia's oil exports have yet to come to fruition. 

A record-breaking 43.2 million Americans are set to travel by car this weekend - up 2.4 percent on last year - according to the American Automobile Association

Last summer, gas prices shot up to their highest level since the 2008 financial crisis, due to a nationwide heatwave which prompted Americans to crank up their air conditioning

However, experts agree this may not last as political unrest in Russia remains a major threat and could push up prices once more. 

Patrick De Haan, head of petroleum analysis at GasBuddy. told CNN: 'The situation is still a bit of a powder keg. It could lead to more explosiveness in oil prices.'

It comes as other Fourth of July holidayers have been told to prepare for a 'flightmare' with up to 2,200 journeys delayed and 1,000 canceled today. 

In total, air passengers have been at the mercy of 35,000 delays this week. 

The chaos prompted the Transport Security Administration to urge vacationers to 'pack some patience' ahead of the holiday.

'As we approach the July 4th holiday travel period, we’re expecting record travel volumes, TSA is staffed & ready to handle the increased volumes with technologies & resources for improved security effectiveness, efficiency, & passenger experience at security checkpoints,' TSA administrator David Pekoske said on Thursday.

'I encourage travelers to pack a bag that starts empty to ensure you don’t have any prohibited items, arrive early, have your ID out and ready, and pack some patience,' he added.