We'll be driving less this holiday weekend -- here's what that will mean

Over the past few years, the Fourth of July has evolved into a significant measure of the nation's economic mood. Most children are out of school, and most parents have the day off, so millions hit the highway for short vacations that reveal changes in consumer optimism, disposable income, and the effects of gas prices.

Seasonal gas hikes are a summer tradition: as demand surges, prices shoot up, generally peaking between June and September. While inconvenient, the hikes usually aren't too significant. In most years, drivers simply dig a little deeper into their pockets to pay the few extra cents per gallon.