I’m not a morning person. In the hours before sunrise, my senses are dulled, and I’m not as observant or sharp as I am later in the day. But I remember one thing with complete clarity: just before we turned onto that gravel road, an orange gas-station light illuminated a sign that read:

Diesel: $6.79 per gallon

I knew diesel and gasoline prices had been elevated for some time, but seeing a price tag like that in rural Kentucky produced a wave of sticker shock. Even amid global conflict, strained oil markets, and widespread inflation at the pump, the price felt exorbitant.

So what causes diesel prices to rise so sharply and who ultimately pays the price?

To understand why diesel often costs more than gasoline, it helps to understand what diesel is.

Diesel gets its name from the German engineer Rudolf Diesel, who developed the prototype diesel engine in 1892. However, the fuel that would eventually be named after the engine, and synonymous with its use, was not widely used until the 1910s-1930s when ocean-faring motorized ships, trains, and trucks began to implement the engines into their designs.

Diesel is not a naturally occurring product, but rather it is refined from Crude oil.

Here’s how it works:

Crude oil consists of hydrocarbon chains with different boiling points. During the refining process, crude oil is heated and separated in a distillation column. The lightest components, such as gasoline, are collected near the top, while heavier components settle toward the bottom. Diesel is drawn from the middle portion of the column, generally at temperatures of roughly 175 to 275 degrees Celsius, or 350 to 530 degrees Fahrenheit.

The resulting distillate is further processed to remove contaminants, including sulfur compounds. In the United States, ultra-low-sulfur diesel is generally limited to 15 parts per million of sulfur.

Diesel engines use a process called compression ignition. Unlike gasoline engines, which use spark plugs to ignite a fuel-air mixture, diesel engines compress air to such a high pressure that it becomes extremely hot. When fuel is injected into the cylinder, it ignites upon contact with the heated air.

This design enables high compression ratios, strong torque output, durability, and efficient energy extraction. Diesel is therefore widely used in long-haul trucks, cargo ships, trains, and heavy equipment used in farming, mining, and construction.

Although alternative technologies are advancing, no single battery or alternative fuel currently matches diesel’s combination of energy density, range, and practicality across every heavy-duty application.

Diesel price increases can feel disproportionate because diesel markets are often structurally tighter than gasoline markets. They are also highly interconnected internationally and vulnerable to supply disruptions.

When distillate inventories are low, even a relatively small disruption can create a significant price reaction. Diesel is traded across borders, and localized shortages can quickly become regional or global problems. Gasoline markets, by contrast, often benefit from broader domestic storage networks and greater production flexibility.

Demand for diesel is relatively inelastic. If prices rise, trucking companies, farmers, construction firms, and shipping operators cannot simply stop using it without disrupting their operations. A truck still needs fuel to deliver food. A farmer still needs fuel to plant and harvest crops. A construction company still needs fuel to operate heavy machinery.

Consumers ultimately feel these increases through higher shipping fees, food prices, and building-material costs. A rise in diesel prices does not automatically create an exponential increase in shipping costs, but it does raise a major operating expense that can compound as goods move through multiple stages of the supply chain. Prices also do not move evenly. The popular adage to describe this phenomenon is “up like a rocket, down like a feather.” Prices jump rapidly when wholesale costs rise, but settle down at a much more lethargic pace. With distillate inventories near multi-decade lows, there’s little cushion to pull diesel back down, even if crude prices soften.

These dynamics might lead you to assume that diesel prices are rising solely because the world’s crude-oil supply is under pressure. That is only part of the story.

The more immediate problem is refining capacity.

Geopolitical conflict can disrupt refineries themselves. Even when crude oil remains available, damaged or offline refineries can reduce the supply of usable diesel. With widespread attacks on these sites across Russia, Ukraine and the Middle East, many processing facilities have been rendered unusable this year. Refineries are complex, capital-intensive facilities, so restoring lost capacity can take months or years.

This is reflected in the diesel crack spread, which measures the difference between the price of refined diesel and the price of crude oil. In simplified terms, it represents the margin a refiner earns from converting crude oil into diesel.

Diesel crack spread figures can vary greatly. As of 10/06/2026, the average crack spread across New York Harbor, U.S. Gulf Coast, and Los Angeles according to calculations generated from EIA Spot Data was $102.25. Regional readings ranged from roughly $95 to $110.

To put that in perspective, the diesel crack was roughly $20 a barrel before the Iran war. At $102, a barrel of diesel sells for about twice what the crude inside it costs, roughly $198 against $96, and that gap is the premium the market is paying for. This too factors in to diesel prices remaining expensive even when crude prices ease.

Diesel prices sometimes need a little outside push to regulate, and this kind of action is happening now. As this article was being written, the current administration signed an executive order temporarily letting truckers run red-dyed diesel on highways. It’s a fuel normally restricted to off-road use because it is exempt from the federal fuel tax. In the same week, he announced that long-time adversary Russia, whose own refineries have been hit by Ukrainian drones, would begin supplying diesel to the US market, starting with 300,000 tons, with the Treasury issuing a temporary license to make it possible. Who pays for that fuel, and when it arrives, remains unanswered.

Both moves treat the symptom. A tax waiver lowers the bill, and a promised Russian deal adds barrels on paper, but neither repairs a refinery, which is where that $100 gap lives. The IEA now expects the recovery of Gulf supply to be deferred until 2027, so relief is likely to be slow. With diesel up roughly 70% since the Iran war began, these acts are exemplary of the tremendous pressure inflated diesel prices create - enough to command complete reversals of domestic and geopolitical policies which echo from the halls of the Whitehouse to the gravel roads of Northern Kentucky.

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