The national average price of regular unleaded fell 1 cent to $2.56 per gallon for the week ending Sept. 9, and reached a level that's 11 cents lower than a month ago and 28 cents lower than a year ago, according to AAA.

Gasoline demand typically falls after Labor Day, and this year was no exception with a decline of about 500,000 barrels per day to 9.4 million. Domestic gasoline stocks fell by 2 million barrels due to exports, according to the U.S. Energy Information Administration.

"Gasoline demand in early September generally declines alongside stock levels as refineries prepare for the switchover to winter-blend gasoline and undergo maintenance," said Jeanette Casselano, AAA spokesperson. "These typical trends mean savings for motorists, leading the way for potentially some of the cheapest gas prices at the end of the year."

State averages range from as expensive as $3.65 in Hawaii to as cheap as $2.16 in Mississippi. Most state averages are 20 to 55 cents cheaper than the same time a year ago.

States with the largest weekly price changes include Ohio (down 13 cents), Illinois (down 7 cents), Michigan (up 4 cents), New Jersey (down 4 cents), Rhode Island (down 4 cents), Maryland (down 4 cents), Massachusetts (down 3 cents), Connecticut (down 3 cents), and Indiana (up 3 cents).

States with the least expensive gasoline include Mississippi ($2.16), Louisiana ($2.17), Alabama ($2.20), Arkansas ($2.23), South Carolina ($2.23), Oklahoma ($2.25), Tennessee ($2.25), Texas ($2.27), Missouri ($2.28), and Virginia ($2.29).

Meanwhile, the average price of diesel fell five-tenths of a cent to $2.971, which is 28.7 cents lower than a year ago.