After three weeks of increase, the national average retail price of a gallon of diesel dipped this week, falling 0.9 cent to $2.87, according to the Department of Energy.

Over the previous three weeks, the U.S. average price had gained 15.3 cents.

Prices across the U.S. regions were mixed, as California, the West Coast, the Gulf Coast, the Midwest, Central Atlantic and New England declined in price, while the overall East Coast, Rocky Mountain area and Lower Atlantic states were up slightly.

The cheapest place to buy diesel is in the Rocky Mountain region at $2.827, while New England is the most expensive area for fuel at $3.065. The Central Atlantic area is also over $3 a gallon.

For state-by-state diesel prices, updated daily, click here.