Retail diesel prices saw an average increase of two cents throughout the United States this week to hit $2.50. The 27-week average price is now at $2.68. The largest increases were in the Lower Atlantic and Gulf Coast regions, where diesel prices jumped three cents. Only the Rocky Mountain region saw a decrease of one cent. The highest retail diesel prices are in the West Coast region at $2.72, while the smallest are in the Gulf Coast region at $2.32.