Retail gasoline prices in Indiana rose to $3.79 per gallon on Sept. 15 following a total power outage at Exxon Mobil's 275,000 barrel per day refinery in Joliet, Illinois. The disruption triggered a 35.5 cent per gallon jump in Great Lakes spot gasoline prices and a 22.5 cent increase for diesel. Higher fuel costs are now moving through retail markets in Illinois, Ohio, and Wisconsin, while Michigan prices climbed on Sept. 14.

Power has been restored at the Joliet facility, but units remain in the process of being reset after an emergency shutdown that caused visible sulfur dioxide flaring. Full operation typically takes several days to a week to resume after an uncontrolled power loss. BP's Whiting refinery in Indiana is also partially down for maintenance, adding further pressure to the Great Lakes fuel supply.