Photo via Wikimedia.

Photo via Wikimedia.

The national average price of gasoline fell 4.2 cents to $3.593 per gallon for the week ending July 21, according to the U.S. Energy Information Administration.

The price of a gallon of regular unleaded is now 8.9 cents lower than a year ago. Its price fell in each of the nine regions tracked by the U.S. Department of Energy. Gasoline is now cheaper than a year ago in every region except the Rock Mountains and the West Coast.

For the week, the sharpest price decline came in the Gulf Coast, where it fell 4.6 cents to $3.394. Gasoline declined only four-tenths of a cent in the Rocky Mountain region.

The average price of gasoline is now at least $3.50 in 32 states and the District of Columbia, according to the AAA's Daily Fuel Gauge Report. Two weeks ago, 40 states were at or above that price level.

Meanwhile, the average price of diesel fell 2.5 cents per gallon to $3.869. Diesel fuel is now 3.4 cents lower than it was a year ago.