The Energy Information Administration, the statistical arm of the Energy Department, said the national average price for a gallon of gasoline as of Aug. 4 was $3.52, more than 3 percent lower than the same time last year.
Motor club AAA reports a national average price Thursday for a gallon of regular unleaded gasoline at $3.47, 18 cents cheaper than one month ago.
EIA said crude oil prices, which account for the bulk of the price at the pump, are down globally because of ample supply compared with demand.
EIA forecasts show retail gasoline prices have been on a general decline since around June. Trend lines suggest the price at the pump should continue to decline slowly through at least September.
Long-term, EIA expects retail gasoline prices will average $3.54 for the year, but drop another 10 cents next year. That's compared with an average $3.51 in 2013.