Lake County drivers are paying roughly 50 cents more per gallon of regular gas than the national average, and the gap traces to a chain of refinery breakdowns about 90 miles south.

Regular unleaded in Lake County averaged $4.74 per gallon as of Oct. 16, according to AAA data compiled by Stacker. The Chicago metro average climbed to $4.83 on Oct. 22, AAA reported, while the national average sat at $4.27. Illinois diesel averaged $6.56 per gallon, down from a record $6.83 on Sept. 23.

Three overlapping refinery disruptions across the Great Lakes region are behind the spike, according to RE Journals.

The ExxonMobil refinery in Joliet, a 275,000-barrel-per-day plant in Will County, suffered a total power outage on Sept. 13 that forced an emergency shutdown. The facility produces roughly 11 million gallons of gasoline and diesel daily and accounts for about 6% of all Midwest refining capacity, according to industry publication ChemNet. Its fuel feeds pipelines serving Illinois, Indiana, Iowa, Michigan and Wisconsin.

ExxonMobil had not finished recovering when a new problem emerged. On Oct. 20, the company shut a 50,000-barrel-per-day catalytic reformer at the same Joliet plant, Texas Energy Report reported. An ExxonMobil spokesperson said Oct. 21 that the company was working to resolve an operational issue but gave no restart timeline.

The Joliet outages coincided with planned maintenance at the Cenovus refinery in Lima, Ohio, which took another 185,000 barrels per day offline starting in September, according to RE Journals. The BP Whiting refinery in Indiana, the Midwest's largest, has also been running with restricted capacity. About 800 BP workers have been locked out since March 19 in a contract dispute with the United Steelworkers, In These Times reported.

What Lake County residents are paying

The Bureau of Labor Statistics reported that gasoline prices in the Chicago-Naperville-Elgin area, which includes Lake County, rose 6.3% from August to September. The gasoline index climbed 28.9% year over year.

Diesel had already been climbing before the worst of the Joliet disruptions. The Lake County Gazette reported that the cheapest diesel in Lake County during the week ending Sept. 5 was $5.04 per gallon, with the county averaging $5.55. Statewide diesel has surged past $6.50 since then.

The pain extends beyond the pump. Suburban school districts that operate their own bus fleets have been among the hardest hit, the Chicago Tribune reported. Naperville Unit District 203, which runs more than 120 diesel buses for roughly 16,000 students, expects to spend an extra $300,000 on fuel this school year if prices hold. Whether Lake Forest School Districts 67 and 115 face similar budget pressure is not yet clear; District 67's board approved its 2026-27 budget in September, but no public diesel-cost estimate has appeared in available district materials.

Gov. JB Pritzker declared Illinois a diesel disaster area on Oct. 6, Shaw Local reported. His executive order directs the Illinois Department of Revenue and the Illinois State Police not to impose penalties for selling or using tax-exempt dyed diesel fuel through Dec. 31.

When prices may ease

Patrick De Haan, head of petroleum analysis at GasBuddy, told the Tribune that diesel prices may decline slightly in the weeks ahead as the Joliet plant resumes operations. Per-gallon diesel had already dropped more than 25 cents since the Sept. 23 peak.

Longer-term relief is uncertain. "A lot of that is a function of the continued evolution in the situation between the U.S. and Ukraine, and the U.S. and Iran," De Haan told the Tribune. "If we see some improvement in tensions there, then we could see some relief."

RE Journals noted that much of the pressure stems from a temporary regional bottleneck and that prices should stabilize as the Joliet refinery returns and BP Whiting's maintenance ends. The Oct. 20 catalytic reformer shutdown complicates that forecast. ExxonMobil has not disclosed a restart date for the unit.