The average retail price of a gallon of gasoline in the United States declined for the first time since mid-December, dropping 5.44 cents over the past two weeks, the nationwide Lundberg Survey showed.

The national average for a gallon of regular gasoline fell to $3.9127 on April 20, from $3.9671 on April 6, according to the survey of gasoline retailers in the continental United States.

Still, drivers are paying 3.27 cents more for a gallon than they did a year ago.

"The decline began in California about six weeks ago," survey editor Trilby Lundberg said, adding that prices peaked there on March 9 at $4.3162 and fell in subsequent surveys by nearly 15 percent to $4.1669.

Drivers in Chicago continued to pay the most at the pump -- $4.26 per gallon -- even though prices fell nearly 19 cents from April 6.

Prices in Tulsa, Oklahoma, remained lowest at $3.52 per gallon.

"If crude oil does not shoot back up we may find another price decline of 5-10 cents in the coming weeks," Lundberg said.

Average diesel prices fell 4.15 cents to $4.1735 compared with two weeks earlier.