WASHINGTON, D.C. --- The U.S. average retail price for regular gasoline decreased, falling 9.1 cents to $2.958 per gallon as of July 23. The Energy Department's Energy Information Administration (EIA) reported that prices were 4.5 cents per gallon lower than this time last year. All regions recorded price drops. East Coast prices fell 4.8 cents to $2.924 per gallon. The Midwest region registered the second largest weekly decrease ever, with prices declining 18.8 cents to $2.984 per gallon. Prices for the Gulf Coast were 5.4 cents less, settling at $2.867 per gallon. In the Rocky Mountain region, prices were $3.038 per gallon, down 5.5 cents during the week but 13.1 cents per gallon above this time last year. West Coast prices, the highest in the nation, decreased 3.8 cents to $3.051 per gallon. The average price for regular grade in California was 4.0 cents lower at $3.118 per gallon. Retail diesel prices remained unchanged at $2.889 per gallon, the EIA reported. Diesel prices were 5.7 cents per gallon lower than at this time last year. Regional diesel prices were mixed, with East Coast prices dropping by 1.4 cents to $2.860 per gallon. In the Midwest, diesel prices rose 0.4 cent to $2.882 per gallon, while the Gulf Coast saw a decline of 0.6 cent to $2.815 per gallon. The Rocky Mountain region gained 1.1 cents, to settle at $2.988 per gallon. The West Coast diesel price grew 3.0 cents to $3.061 per gallon, 1.4 cents per gallon higher than at this time last year. California diesel prices also rose, by 1.1 cents, to $3.158 per gallon.