Photo by Vince Taroc.

Photo by Vince Taroc.

The national average price for a gallon of regular unleaded fell 2 cents to $2.54 per gallon to start the Thanksgiving holiday week that's expected to see the most travel in 12 years, according to AAA.

The per-gallon price is now 40 cents more than a year ago. Motorists can find gas for $2.50 or less at 55% of fuel stations in the country.

"Nearly 46 million Americans will travel more than 50 miles away from their home by car this holiday," said Jeanette Casselano, AAA spokesperson. "Many will be thankful to see gas prices trending cheaper in cities across the country. Since 2014, the national gas price average has dropped one to 5 cents heading into the Thanksgiving week."

States with the largest yearly increases include Alaska (+63 cents), Illinois (+59 cents), Indiana (+58 cents), Minnesota (+55 cents), Wisconsin (+54 cents), California (+52 cents), Michigan (+51 cents), Kansas (+49 cents), Iowa (+47 cents), and Colorado (+47 cents).

States with the least expensive gas prices include Alabama ($2.25), Mississippi ($2.26), South Carolina ($2.27), Texas ($2.28), Arkansas ($2.29), Oklahoma ($2.31), Virginia ($2.31), Tennessee ($2.31), Louisiana ($2.33), and Missouri ($2.35).

Meanwhile, the average price of a gallon of diesel fell three-tenths of a cent to $2.912, which is 49.1 cents higher than a year ago, accordin to the U.S. Energy Information Administration.