The United States on-highway diesel fuel price for the week of April 15, 2019 averaged $3.118 per gallon. This is the eighth consecutive weekly increase. Every region in the country experienced a slight increased. California continues to climb near the $4.00 per gallon price at $3.967. On the other end of the spectrum, the only region in the country that is under $3.00 per gallon is the Gulf Coast region at $2.889.