The national average price for a gallon of regular unleaded gasoline in the United States is falling as refineries resume production, motor club AAA said.

AAA reports a national average retail price for a gallon of regular unleaded gasoline at $2.41, about one cent less than Monday. The price has held more or less steady over the course of a month, though prices spiked early in the season because of refinery problems in California and the Midwest.

AAA said the national average price for gas has declined for 18 of the past 24 days.

"The status of regional refineries continues to be a driving factor for gas prices in many parts of the country," the motor club said in a weekly status report. "However, while several weeks ago it was refineries going offline and driving prices higher in the Midwest and West Coast, today it is those facilities resuming production that has driven prices lower in the same regions."

California's state average price for regular unleaded of $3.20 per gallon is about 20 cents less than it was one month ago. For Illinois, which has the highest state average in the Midwest, Tuesday's average price of $2.64 was about 2 cents less than Monday, but still about 15 cents above the price one month ago.

Gas prices tend to peak early in the year as refiners shift from a winter blend of gasoline to a summer blend, which is more expensive to produce because of additional environmental measures. The early season peak in prices usually occurs around early February.

The national average price for gas is $1.14 less than this date in 2014.