The average price of a gallon of self-service regular gasoline in Riverside County dropped Friday to its lowest amount since July 21, 2021, decreasing 1.1 cents to $4.27. The average price has dropped 12 of the past 13 days, decreasing 6.5 cents, according to figures from the AAA and Oil Price Information Service. It dropped 11 consecutive days, then rose two-tenths of a cent Thursday.