The average U.S. price of regular-grade gasoline jumped 6 cents over the past two weeks to $3.02 per gallon. That’s a little over a dollar higher than a year ago. The costs of crude oil and ethanol are also on the rise ahead of the summer peak driving season. The highest average price in the nation right now is $4.16 a gallon San Francisco. The lowest average is $2.55 in Baton Rouge, Louisiana. Go Mart, Kroger, and Exxon stations around Charleston have prices around $2.70.