The national average price for a gallon of unleaded slipped eight-tenths of a cent to $2.793 per gallon for the week ending July 6, according to federal records.

The per-gallon price is now 88.5 cents lower than it was a year ago and incrementally lower in six of the nine regions tracked by the U.S. Environmental Information Administration. Gasoline fell 2.1 cents to $2.521 in the Gulf Coast region, and increased 1.9 cents to $2.81 in the Rocky Mountain region.

Among states, Alaska remains at the top with the costliest cast at $3.484 per gallon. The average price is above $3 per gallon in six other states. The cost is below $2.50 per gallon in four states, and South Carolina ($2.428) has the least expensive gasoline, accoring to the AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of a gallon of diesel fell 1.1 cents to $2.832, which is $1.081 less than a year ago.