Retail diesel prices in the United States soared past $5 a gallon, reaching a milestone seen only once before, according to GasBuddy, the fuel markets tracker. Economists warn that the surge could slow global economic activity. Diesel is essential for freight and manufacturing, and rising fuel costs are likely to push up the price of goods for consumers. The spike also presents a potential challenge for US President Donald Trump, with his Republican Party preparing for midterm elections in November. GasBuddy data shows that Monday’s national average is the second time diesel has topped $5, the first being in December 2022, when global oil markets were still unsettled by Russia’s invasion of Ukraine.

The current escalation comes amid the US-Israeli conflict with Iran, now entering its third week. The Middle East is a major supplier of diesel and the crude oil best suited for its production, and Iran’s near-total blockade of the Strait of Hormuz is estimated to impact 10–20% of global seaborne diesel supplies. Cuts to crude flows to Asian refineries have forced many plants to scale back production, further tightening global availability, Reuters reported.Patrick De Haan, head of petroleum analysis at GasBuddy, said in a blog post on Monday, “until we see a meaningful resumption of oil flows through the Strait of Hormuz, upward pressure on fuel prices is likely to persist.”Despite interventions, including a historic release of oil reserves by industrialised nations, fuel prices have shown little sign of easing. GasBuddy also reported that US gasoline prices averaged $3.76 per gallon at 6:10 pm EDT, the highest since October 2023.