The national average price of a gallon of regular unleaded declined 4 cents to $2.84 and a level that has not been this low since early May, according to AAA.

"July gas prices have been on a roller coaster ride, but appear to be on a downward slope at the moment," said Jeanette Casselano, AAA spokesperson. "If demand and supply stay consistent, prices have the potential to stabilize barring any major events — geopolitical or natural disasters. The market is also following this up-and-down trend lately. Last week, crude prices dropped below $70 per barrel for the first time since June, but then returned above the price point to close out the week."

Gasoline is now 2 cents cheaper than a month ago and 57 cents higher than a year ago. For the week, only Hawaii saw its average price increase (by 1 cent to $3.78) and Montana was the only state that remained unchanged ($2.93). The other 48 states saw declines of, in some cases double digits. In the past month, prices fell in New Mexico by 13 cents ($2.78) and Arizona by 12 cents ($2.94).

The cheapest gasoline can now be found in Alabama ($2.54), South Carolina ($2.54), Mississippi ($2.54), Arkansas ($2.58), Louisiana ($2.58), Oklahoma ($2.60), Virginia ($2.61), Tennessee ($2.61), Texas ($2.61), and Missouri ($2.61).

Meanwhile, the average price of a gallon of diesel fell 1.9 cents to $3.22 for the week, which is 71.3 cents higher than a year ago, according to the U.S. Energy Information Administration.

Related: Controlling Fuel Costs as Gas Prices Rise