National and state gasoline prices continued to decline a week before Memorial Day with a 6-cent decline during the week ending May 20 as crude oil prices have remained stable, according to AAA and the U.S. Energy Information Administration.

The national gasoline price fell 1 cent to $2.85, which was offset by price increases in the Midwest caused by ongoing refinery maintenance, said Jeanette Casselano, AAA's spokesperson.

"Gas prices are getting cheaper for the majority of motorists despite the fact that U.S. gasoline stocks sit at a 7-million-barrel deficit year-over-year," Casselano said. "Crude oil prices have remained relatively stable the past few months, which is one reason helping gas prices be cheaper than last year at this time. Today, motorists can find gas for $2.75 or less at nearly half of all gas stations in the country."

The national price is now 1 cent lower than a month ago and 7 cents lower than a year ago.

States with the largest weekly changes include Ohio (up 11 cents), Michigan (up 7 cents), Florida (down 7 cents), Illinois (down 5 cents), North Carolina (down 4 cents), South Carolina (down 4 cents), Delaware (down 4 cents), Mississippi (down 4 cents), Indiana (up 3 cents), and Georgia (down 3 cents).

States with the least expensive markets now include Louisiana ($2.45), South Carolina ($2.45), Alabama ($2.45), Mississippi ($2.45), Arkansas ($2.50), Tennessee ($2.54), Missouri ($2.54), Oklahoma ($2.56), Texas ($2.57), and Kansas ($2.58).

Meanwhile, the average price of a gallon of diesel fell three-tenths of a cent to $3.163, which is 11.4 cents lower than a year ago, according to the EIA.