Gas prices fluctuate widely due to a variety of factors.”Smith said diesel prices have not changed much in Washington since the beginning of the year and took a shot at gasoline producers. According to media reports out of Seattle, this is the first time Washington has posted the nation’s highest average price per gallon. De Haan predicts Washington and California will battle it out as the state with the highest gas prices in the nation for some time to come. “Washington could remain at or above California’s levels.”AAA also tracks gasoline prices across the country and its data roughly parallel with GasBuddy’s. According to AAA, the average price for a gallon of regular on Tuesday came to $4.912 in Washington and $4.868 in California.