For the first time since the week ending Oct. 23, 2005, the national average price for a gallon of diesel topped the $3 mark. Jumping 7.5 cents, it increased to $3.055 for the week ending Aug. 6, according to the Energy Information Administration.
The Rocky Mountain region, with a 15.6-cent increase to $3.208, now has overtaken California as the most expensive region in which to fill up. California rose just 3.7 cents to $3.13.
The cheapest region was the Gulf Coast -- $2.988 after rising 6.3 cents.