The average price for a gallon of diesel fell six cents to $2.967 for the week ending Sept. 3, according to the Energy Information Administration.

All regions posted a price drop, including California, which was the only region that transitioned 100% of its on-highway diesel to ultra-low sulfur diesel on Sept. 1.

See California makes smooth ULSD switch

Prices were the most stable in California, as it dropped a relatively modest 2.5 cents to $3.175. The largest drop was in the Midwest, after an 8.9-cent slide to $2.937. The Lower Atlantic region was the cheapest in which to fill up at $2.85 after a 4.7-cent fall. The Rocky Mountain region is once again the most expensive at $3.318, in spite of a 2.8-cent price break.