Diesel fuel prices have held flat across the U.S. for eight straight weeks to begin 2017 with a high of $2.597 in the week ending Jan. 9, and a low of $2.558 in the week ending Feb. 6.

Prices during the most recent week landed in the middle at $2.577 per gallon, a half-cent increase from the previous week, according to the Department of Energy’s weekly report.

Fuel prices increased in all regions except California during the week, with the most significant increase coming in the Rocky Mountain region, where prices rose 3.4 cents.

California, which saw a dip of four-tenths of a cent during the week, still has the nation’s highest prices at $2.962 per gallon, followed by the Central Atlantic and West Coast less California regions at $2.772 per gallon.

The cheapest fuel can be found in the Gulf Coast region at $2.433 per gallon, followed by the Midwest region at $2.499 per gallon.

Prices in other regions, according to the DOE, are:

New England – $2.658
Lower Atlantic – $2.533
Rocky Mountain – $2.582
ProMiles’ numbers during the same week had diesel prices increasing by 1.7 cents to $2.524 per gallon nationwide.

According to ProMiles’ Fuel Surcharge Index, the most expensive diesel can be found in California at $2.896 per gallon, and the cheapest can be found in the Gulf Coast region at $2.434 per gallon.