The on-highway diesel fuel prices in the U.S. for the week of 7/31/17 averaged $2.531. The price rose on average of 1.6 cents. This is the highest price in two months and Saudi Arabia announced it would make additional cuts in oil production. Diesel cost 13 cents more than it did a year ago. The price is up in every region of the country. California remains the highest at $2.907. The Gulf Coast is lowest at $2.359.