The average price of a gallon of unleaded rose 2.7 cents to $2.691 for the week ending May 11, marking a month-long run of rising prices, according to federal records.

With the increase, gasoline prices now stand 97.7 cents lower than a year ago, according to the U.S. Energy Information Administration.

Prices rose in nine of the nine regions tracked with the sharpest increase coming in the Rocky Mountain region of 6.7 cents to $2.634. Gasoline on the West Coast remains the most expensive at $3.444 with California and $2.948 with the state excluded. Gulf Coast gasoline is the cheapest at $2.436 on average.

Among states, five now have gasoline prices of at least $3 per gallon, including California ($3.717), Hawaii ($3.226), Nevada ($3.218), Alaska ($3.153), and Oregon ($3.001). Fourteen states now have gasoline costing less than $2.50 with South Carolina ($2.366) again at the end of the list, according to AAA's Daily Fuel Gauge Report.

Meanwhile, diesel prices increased 2.4 cents to $2.878 per gallon. Diesel now costs $1.07 less than a year ago. Diesel prices also increase in nine regions.