WASHINGTON, D.C. --- The U.S. average retail price for regular gasoline dropped 6.7 cents to $2.771 per gallon as of Aug. 13. That's 22.9 cents lower than last year, the Energy Department's Energy Information Administration (EIA) reported last week. Prices fell for the fourth week in a row, reaching the lowest national average price since April 2. All regions recorded price declines. East Coast prices fell 7.0 cents to $2.751 per gallon. Midwest region prices decreased 5.9 cents to $2.769 per gallon. Prices for the Gulf Coast were 6.7 cents less, settling at $2.681 per gallon, the lowest regional average in the country. In the Rocky Mountain region, prices were $2.880 per gallon, down 6.5 cents and the highest regional average in the nation. West Coast prices dropped 7.6 cents to $2.879 per gallon. The average price for regular grade in California was 8.8 cents lower at $2.928 per gallon. Continuing the fluctuating trend in recent weeks, retail diesel prices were down 5.1 cents per gallon, reaching $2.847 per gallon. Diesel prices were 21.8 cents per gallon lower than at this time last year, the EIA said. All regional diesel prices fell, with East Coast prices dropping by 4.6 cents to $2.820 per gallon. In the Midwest, diesel prices fell 5.2 cents to $2.835 per gallon, while the Gulf Coast saw a decrease of 5.3 cents to $2.771 per gallon. The Rocky Mountain region declined 3.2 cents to settle at $2.980 per gallon. The West Coast average diesel price dropped by 5.8 cents, but remained the highest priced region in the nation at $3.019 per gallon. California diesel prices fell by 8.6 cents to $3.054 per gallon, 16.6 cents per gallon lower than at this time last year.