Gas prices.

It's all supply and demand driven. In California, they have a summer mix gasoline which is a little special for out of state refiners to make. Sooooooo, any excuse is a good one to raise prices. In some cases, when a local refinery goes down, (for what ever reason) available fuel has to shipped farther through pipelines to get to the local storage depot. That's a good excuse as any to raise wholesale prices which quickly translate to a price increase at the retail pump.

(Everybody) Stop buying gas for a month. (not going to happen) See what happens next as the oil tankers line up at the offshore terminals.

Chum lee