US Diesel Retail Price Tops $6.50 a Gallon for First Time, Adding to Inflation Pressure Before Midterms

The U.S. national average diesel retail price rose to a record $6.505 per gallon, according to AAA data released September 21, 2026, up about 70% since the outbreak of the U.S.-Iran conflict and more than 87 cents in September alone, surpassing the previous peak of $5.81 set during the early weeks of the Russia-Ukraine war.