The weekly retail on-highway diesel prices released by the Energy Department Monday (July 2) show the cost of diesel fuel fell 4 cents from last week. The national average price per gallon declined for the fifth straight week to $1.407 - the cheapest diesel has been since mid April.

The biggest drop from a week ago was in the Rocky Mountain region. Diesel there decreased more than 6 cents to about $1.50 per gallon. The cost of fuel in the region has plummeted more than 12 cents in the past month.

The lowest prices nationally are in the Lower Atlantic region. Fuel there dipped more than 2.5 cents per gallon to $1.36. The cost of fuel in the region has dropped more than 7 cents in the last five weeks.

The highest prices nationally are once again found in the state of California. Fuel there costs $1.62 per gallon - down about 1 cent from last week.

The remaining regions' price per gallon is as follows: East Coast, $1.40; New England, $1.51; Central Atlantic, $1.48; Midwest, $1.37; Gulf Coast, $1.38; and West Coast, $1.56.

The Department of Energy reports the average price of self-serve diesel each Monday evening. Prices are based on a survey of 350 diesel service centers nationwide and include taxes.