The national average price of a gallon of unleaded gasoline increased 6.8 cents to $2.137 for the week ending April 18, federal records show.

The average price is now 34.8 cents lower than a year ago, as it increased in nine regions tracked by the U.S. Energy Information Administration. Prices increased most in the Midwest, where the average price added 9.2 cents to $2.057. New England and the Central Atlantic regions increased 8.3 cents ($2.155) and 8.2 cents ($2.171) respectively. Eight regions are now above $2 per gallon. Gulf Coast gasoline is now $1.91.

Among states, California gasoline ($2.785) remains the most expensive, while Mississippi gasoline ($1.891) is the cheapest. Thirteen states now have gasoline under $2, according to the AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of a gallon of diesel increased 3.7 cents to $2.165. Diesel is now 61.5 cents lower than a year ago.