The national average gasoline price fell 3 cents to $2.86 for the week ending May 13, which represents the first significant decline since earlier this year, when a succession of price increases added about 60 cents to the per-gallon price, according to AAA.

The current price is 4 cents cheaper than a month ago and the same price as a year ago.

Gasoline prices are decreasing in spite of recent reports from the U.S. Energy Information Administration showing an increase in demand to summer levels and declining gasoline supply.

"There are many factors that could quickly push up prices in the coming weeks, including the impact of Chinese tariffs, weather, a major draw in gasoline stock levels, a spike in demand, or the volume of Memorial Day weekend travel," said Jeanette Casselano, AAA spokesperson. "Pump price movements this week will indicate if motorists will continue to see cheaper gas prices or if this was just a one-week fad."

States with the least expensive markets include Alabama ($2.48), Louisiana ($2.49), Mississippi ($2.49), South Carolina ($2.49), Arkansas ($2.53) Oklahoma ($2.57), Texas ($2.57), Tennessee ($2.57), Missouri ($2.58), and Virginia ($2.61).

States with the largest yearly changes include California (up 38 cents), Arizona (up 20 cents), Nevada (up 20 cents), Ohio (down 18 cents), Delaware (down 16 cents), Washington (up 15 cents), Oregon (up 14 cents), Kentucky (down 14 cents), Michigan (down 12 cents), and Alaska (up 11 cents).

Meanwhile, the average price of diesel fell 1.1 cents to $3.16 per gallon, which is 7.9 cents lower than a year ago, according to the EIA.