Missoula, MT (KGVO-AM News) - Montana gas prices have slightly dropped in back-to-back weeks after two weeks of significant increases. “Average gasoline prices in Montana have fallen 4.7 cents per gallon in the last week, averaging $4.23 per gallon today,” De Haan said. “Prices in Montana are 31.1 cents per gallon higher than a month ago and stand $1.02 per gallon higher than a year ago." “The national average is up 9.5 cents per gallon from a month ago and stands 85.6 cents per gallon higher than a year ago. READ MORE: Montana Gas Prices Drop But Still Sit $1 Over Last Year's AverageDe Haan said average gasoline prices declined in 47 states over the last week while diesel fell in 39.