On-highway diesel prices declined, albeit slightly, for the 13th week in a row, according to figures released June 9. The national average, at-the-pump diesel price decreased from $1.423 to $1.422 a gallon, the Energy Information Administration reported.

Three areas still retain the dollar-fifty mark: New England, where the average price is $1.563; the Central Atlantic, where the price is $1.555; and California, where the price is $1.517. The lowest average price of $1.365 is in the Gulf Coast region.

The remaining regions' prices per gallon are as follows: the Midwest at $1.418; the Lower Atlantic states, where the price is $1.381; the West Coast, where the price is $1.473; the Rocky Mountain region, where the price is $1.440; and on the East Coast, where the price is $1.441.