Labor Day road-trippers can rejoice -- this holiday weekend’s gasoline prices will be the cheapest they have been in four years. Gasoline prices in the U.S. fell to the lowest average price on the Monday before Labor Day since 2010, at $3.45 per gallon, said the Energy Information Administration, or EIA.

That’s a quarter a gallon less than the average price at the end of June.

The dip is primarily due to a slide in crude-oil prices to about $102 per barrel in August, compared with prices of $110 to $113 the past few years. Before that, the recession dragged down oil prices.

Still, the prices vary widely by region. Consumers in the South and Southeast, where many oil refineries are located, pay significantly less for gas than do those on the West Coast.

gasprices Gas prices vary by U.S. region. Photo: Energy Information Administration

In June, crude-oil costs accounted for 67 percent of the price of gasoline, according to EIA. Refining the oil into gasoline accounted for 14 percent; federal and state taxes, 12 percent; and transporting and marketing, 8 percent.