U.S. retail diesel prices hit an all-time high of $5.85 per gallon on September 4, 2026, surpassing the previous June 2022 record of $5.78 per gallon. In a new insight, Director of Energy and Environmental Policy Shuting Pomerleau discusses the implications of the increase in U.S. retail diesel prices.

Key points:

• As U.S, diesel prices rose, the U.S. Gulf Coast diesel crack spread (a measure of profit margins) surged past $100 per barrel on September 1, 2026—a fivefold jump from the pre-Middle-East-conflict baseline of approximately $20 per barrel.
• The diesel price shock is driven by several factors: the six-month de facto closure of the Strait of Hormuz, Russia’s diesel export ban, U.S. refinery utilization maxing out at 98 percent, yield competition from high-margin jet fuel, and the short-run demand inelasticity of commercial freight and agriculture.
• The average pump price increase of approximately $1.61 per gallon since the start of the U.S.-Iran conflicts added roughly $34.8 billion in direct diesel fuel costs for commercial transport from late February-August 2026, cascading through supply chains to U.S. consumers via higher freight charges and elevated goods prices; this added cost will grow in the days ahead if the pump price of diesel fuel reaches $6 per gallon, as some analysts predict.

Read the analysis.