Gas Prices Down Just Slightly Over 2 Weeks The average U.S. price of a gallon of gasoline dipped by less than one penny - about a third of a cent - over the past two weeks. That's according to the Lundberg Survey of fuel prices, released Sunday, which puts the price of a gallon of regular at $3.83. Midgrade costs an average of $4.00 a gallon, and premium is $4.12. Diesel held steady at $4.14 a gallon. Of the cities surveyed in the lower 48 states, Jackson, Miss., has the nation's lowest average price for gas at $3.51. Chicago has the highest at $4.25. In California, the lowest average price was $4.03 in Bakersfield. San Francisco has the highest at $4.19. The average statewide for a gallon of regular was $4.11.