The average price for a gallon of diesel nationally increased one cent to $3.065, but it went up in some regions by 10 cents due to spot shortages, according to the Energy Information Administration.
The Rocky Mountain region remained the most expensive region at $3.311, up 10.3 cents. The West Coast was second at $3.218, up 10.5 cents.
Supplies were reduced in the Northwest after BP's announcement that it had shut down the nation's largest oil field, in Alaska. In the Rocky Mountain region, there were shortages due in part to the transition to ultra-low sulfur diesel. The Lower Atlantic region had the biggest drop, down 2.5 cents to $2.964, and remained the lowest-priced in the nation.