The price of a gallon of unleaded gasoline remained essentially flat by falling five-tenths of a cent to $2.322 for the week ending Sept. 28, according to federal data.

Gasoline prices have been on a steady decline this year since peaking in June just above $2.80 per gallon. The national price is now $1.032 lower than a year ago, according to the U.S. Department of Energy. This level was last tested in late February.

Prices remained mostly flat in the agency's nine regions. Prices fell more sharply in the Rocky Mountain (6.7 cents to $2.539) and West Coast (7.5 cents to $2.836) regions.

Among states, only Alaska now comes in with gasoline costing more than $3 per gallon ($3.036). Gasoline in 11 other states costs at least $2.50, and six states now have gasoline costing less than $2 per gallon. In South Caroline and Mississippi, gasoline costs an average of $1.961, according to the AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of diesel fell 1.7 cents to $2.476 per gallon. Diesel fuel is now $1.279 less than a year ago.