The national average for a gallon of unleaded gasoline increased only slightly, six-tenths of a cent, to $2.78 per gallon for the week ending June 1, according to federal records.

The average price is now 91 cents lower than the same time a year ago. For the week, prices in the nine regions tracked by the U.S. Energy Information Administration fell in three regions and increased in six regions. The sharpest decline came on the West Coast with a 4.3-cent decline to $3.444. Most increases in the regions were incremental with the Midwest showing a 3.9-cent increase.

Gasoline remained above $3 per gallon in seven states with California at the top of the country at $3.695 per gallon. Eight  states have gasoline that costs less than $2.50 per gallon with Mississippi displacing South Carolina as the lowest average price gasoline ($2.441).

Meanwhile, the average diesel gallon price fell five-tenths of a cent to $2.909. Diesel now costs $1.009 less than a year ago.