CAMARILLO, Calif. (AP) — The average U.S. price of regular-grade gasoline plunged 55 cents over the past month to $4.35 per gallon.

That’s according to AAA’s national gas price tracking, As of Monday morning, Indiana sits slightly higher than the national average at $4.37 per gallon. Illinois’ average is reportedly $4.82.

Industry analyst Trilby Lundberg of the Lundberg Survey said Sunday that the continued decline comes as crude oil costs also fall.

“Further drops at the pump are likely as the wholesale gasoline price cuts continue making their way to street level,” Lundberg said in a statement.

While the cost has dropped as of late, the overall trend in prices remains high compared to one year ago when the country saw a cost of $3.15 per gallon.

Looking locally at the Wabash Valley, AAA ranks Vermillion County as the second highest average in the state, just 1 cent below Hamilton County’s $4.67 per gallon. In contrast, Martin County has the best price on the Indiana side of the valley with an average of $4.11. Vigo County was reporting an average of $4.46 as of Monday morning.

While statewide Illinois’ average is higher than Indiana’s, that’s not always the case depending on which county you visit. Edgar and Clark counties reported average costs of $4.20 and $4.24 respectively. While Vermilion County reports the highest price on the Illinois side of the Wabash Valley at $4.58.

Nationally California ranks as the state with the highest average price per gallon at $5.73 with San Luis Obispo county having an average cost of $6.05. Texas has the lowest state average at $3.85 per gallon.

According to a Trilby Lundberg survey, the average price of diesel dropped 22 cents over two weeks to $5.55 a gallon.

The Associated Press contributed to this report