CAMARILLO, Calif. (AP) — The average U.S. price of a gallon of gasoline has dropped 14 cents over the past two weeks. The Lundberg Survey of fuel prices released Sunday says the price of a gallon of regular is $3.38. Midgrade costs an average of $3.58 a gallon, and premium is $3.71. Diesel was down 4 cents at $3.92 gallon. Of the cities surveyed in the Lower 48 states, St. Louis has the nation's lowest average price for gas at $3.01. San Francisco has the highest at $3.88. In California, the lowest average price was $3.74 in Sacramento. The average statewide for a gallon of regular was $3.83, a drop of 14 cents.