Filling up at the pump may be the last thing you do before hitting the road for the Fourth of July weekend, but it’ll cost you. Across California, the average price for regular is 4.28 a gallon. In Santa Barbara County, it’s 4.26 a gallon. San Luis Obispo county averages 4.47. According to KSBY, rising gas prices are also affecting small businesses that currently offer delivery. California has the highest gas tax in the nation at 51 cents a gallon.