The national average gasoline price continues to move lower, falling to a level not seen since the Independence Day holiday in 2005, according to AAA.

A gallon of regular unleaded costs $2.23, and gasoline prices fell in 46 states for the week ending July 3. Only Illinois, Oklahoma, and Washington, D.C. saw prices increase. Hawaii and Maine remained flat.

"The combination of tepid demand and increased gasoline and crude output continues to put downward pressure on gas prices," said Jeanette Casselano, AAA's spokesperson. "While holiday gasoline demand is likely to reach new highs, it will probably not be enough to cause a significant increase on the price of gasoline in the coming week."

In the past week, gasoline declined 3 cents. It's now 15 cents lower than a month ago and 4 cents lower than a year ago.

States with the least expensive gasoline include South Carolina ($1.90), Alabama ($1.96), Oklahoma ($1.97), Mississippi ($1.97), Tennessee ($2.00), Arkansas ($2.00), Missouri ($2.00), Virginia ($2.01), Texas ($2.02) and Louisiana ($2.04).

States with the most significant monthly declines include Ohio (28 cents), Florida (23 cents), Michigan (23 cents), Indiana (19 cents), Delaware (19 cents), Kentucky (18 cents), Texas (18 cents), Maryland (16 cents), Iowa (16 cents) and California (16 cents).

Meanwhile, the average price of a gallon of diesel increased seven-tenths of a cent to $2.472. Diesel is now 4.9 cents higher than a year ago.