Gasoline prices have been on the upswing for the past three weeks with the price of a gallon on unleaded climbing 9.4 cents to $2.664 for the week ending May 4.

The weekly increase marked the third consecutive week of increasing gasoline prices, which remain $1.02 lower than a year ago, according to data from the U.S. Energy Information Administration.

Prices rose across the U.S. with nine of the nine regions tracked showing an increase. The sharpest hike came on the West Coast with a 23.4-cent increase to $3.416. The West Coast without California registered the second-highest increase of 16 cents to $2.909.

Among states, California gasoline remains significantly higher than other states, averaging $3.707 per gallon, according to the AAA's Daily Fuel Gauge Report. Fuel in Hawaii, Nevada, and Alaska also costs more than $3 per gallon. On the lower end of the list, 11 states now have gasoline prices averaging less than $2.40. South Carolina's $2.327 average price is the nation's lowest.

Meanwhile, the average price of a gallon of diesel increased 4.3 cents to $2.854. Diesel fuel is now $1.11 less than it was a year ago.