The national average diesel fuel price hit $5.38 per gallon on Friday, up from $3.61 a year earlier, according to data from the American Automobile Association. In California, the most populous state, the diesel price hit a record $7.17 per gallon. The diesel price in Washington state also soared to an all-time high of $6.55 per gallon, contributing to a cost crunch for truckers who pay fuel bills soon after purchase, but customers often have 30 days or longer to pay for the transport. Despite this, off-contract spot rates are still about 25% higher than they were a year ago.