Diesel prices in the U.S. crept upward last week, continuing a three-week streak of modest increases, according to the latest numbers from the Energy Department.

The average price of on-highway diesel fuel increased by half a cent last week, hitting $2.577 per gallon at the pump. The price is now nearly 59 cents more expensive than it was in the same week of 2016.

Across the country, prices were up or flat, depending on the region. The largest increase hit the Rocky Mountain states at 3.4 cents per gallon. The smallest change was seen in both New England and the Gulf Coast, where prices were flat for the week.

The average price of regular gasoline in the U.S. was up 1.2 cents last week, rising to $2.314 per gallon at the pump. The price is currently around 53 cents per gallon more expensive than it was a year ago at this time.

Gasoline prices varied up and down regionally with the largest increase hitting the West Coast at 4.6 cents per gallon. Prices were down by 2.4 cents per gallon last week in the Central Atlantic region.

The crude oil market saw more of the same as of the morning of Feb. 28, as offsetting forces from Middle East and U.S. oil production have kept prices from increasing or decreasing significantly for months now.  

The Organization of the Petroleum Exporting Countries has so far complied with its agreement to reduce or freeze oil production to meet lower global demand and improve prices. However, by bringing prices up from the lows seen in 2016, U.S. oil production has rallied, dampening crude oil pricing gains expected from the OPEC deal. According to a report on CNBC.com, oil drillers in the U.S. were operating 602 rigs last week, the most since October. 2015.