The national average price of gasoline fell 3 cents to $2.43 for the week ending Dec. 18 and has reached a level that's 12 cents cheaper than a month ago, according to AAA.

Despite the recent price decline, the national average price is now 20 cents higher than it was a year ago. Gasoline prices increased in only two states — Indiana (up three cents) and Hawaii (up 1 cent).

AAA expects more than 97 million Americans to hit the road this week for the holidays, which would be the most on record.

"At 20 cents more per gallon than the same time last year, pump prices don't seem to be a deterrent for today’s travelers," said Jeanette Casselano, AAA spokesperson. "The good news is that in most states, gas prices are 12 cents less than they were a month ago. So today, motorists can find gas for $2.50 or less at 71 percent of gas stations in the country."

Weekly gasoline inventories increased 5.7 million barrels, according to the U.S. Energy Information Administration (EIA). Demand has crossed the 9-million-barrel level. Moving forward, gasoline prices should continue to decline due to weaker winter demand.

The states with largest yearly increases include Alaska (54 cents), California (43 cents), Montana (42 cents), Oregon (38 cents), North Dakota (36 cents), Colorado (35 cents), Hawaii (34 cents), Wyoming (34 cents), Washington (34 cents) and Idaho (33 cents).

States with the least expensive gasoline include Missouri ($2.16), South Carolina ($2.18), Alabama ($2.18), Oklahoma ($2.18), Mississippi ($2.18), Texas ($2.18), Arkansas ($2.19), Tennessee ($2.22), Louisiana ($2.23), and Virginia ($2.24).

Meanwhile, the average price of a gallon of diesel fell nine-tenths of a cent to $2.901, which is 37.4 cents higher than a year ago.