I live in the NW and traveled to CA on Business this week. I thought something was interesting, I noticed that regular gas was higher in price, we are paying mid $5 range and in CA it was in the low $6 for regular, but here Diesel is about $1 more than regular where in CA, Diesel seemed to be about the same price as premium. So, Diesel is similar in price in WA as it is in CA. I think we are paying $6.39 or $6.49 per gallon and I saw Diesel around $6.59 to $6.89 in CA...
The real truth is that diesel should be cheaper than regular since it is easier to refine and starts as a biproduct. Not sure why we are paying more other than it helps to increase the cost of transportation and goods. Helping our economy.