The average U.S. price of a gallon of gasoline has dropped a penny over the past three weeks.
The Lundberg Survey of fuel prices released Sunday says the price of a gallon of regular is $3.59. Midgrade costs an average of $3.77 a gallon, and premium is $3.91.
Diesel remained unchanged at $3.90 gallon.
Of the cities surveyed in the Lower 48 states, Charleston, S.C., has the nation's lowest average price for gas at $3.22. Chicago has the highest at $4.04.
In California, the lowest average price was $3.79 in Sacramento. The highest was in Los Angeles at $4.02. The average statewide for a gallon of regular was $3.95, a decrease of 6 cents.