The AAA national average for a gallon of regular gasoline hit $4.104 on Friday, April 4. [1] Two days ago, when this paper reported the price at $4.06, the figure felt like a milestone. It was not. It was a waypoint. The price has risen every day this week.

California is where the numbers stop resembling anything Americans have seen before. Regular gasoline statewide averaged $5.915. [1] Diesel averaged $7.559 per gallon -- an all-time record for any state, surpassing the previous California diesel high of $7.522 set the day before. [2] The record before that, $7.012, was set in June 2022, after Russia invaded Ukraine. The war in Iran has blown through it by more than fifty cents in a week.

San Diego, which ought to benefit from proximity to Pacific refineries, is instead paying $7.036 for diesel. [3] The San Diego Union-Tribune reported that local trucking companies are weighing whether to park their rigs rather than fill them. When the cost of driving a truck exceeds the revenue the truck generates, the truck stops moving. That is not a metaphor. It is arithmetic.

The geography of diesel pain extends well beyond California. NBC Los Angeles reported the $7.559 statewide diesel figure on Thursday evening, noting it eclipsed Wednesday's record. [2] GasBuddy's Patrick De Haan has been cataloging the acceleration on X, identifying five states where average diesel prices have risen more than $2 per gallon in a single month. [4] California leads at $2.47 above its level one month ago. Hawaii, Washington, Nevada, and Oregon follow. The increases are without precedent in the GasBuddy dataset.

The diesel market matters more than the gasoline market because diesel moves the economy. Every long-haul truck, every freight train, every agricultural tractor, every construction vehicle runs on diesel. When diesel doubles, the cost of moving food from farm to warehouse to store doubles with it. The lag between the pump and the shelf is measured in weeks. The lag between the pump and the construction bid is measured in days. The lag between the pump and the Amazon delivery surcharge is measured in whatever Jeff Bezos decides it should be.

AAA's state-by-state data confirms that no corner of the country has been spared. [5] The cheapest states -- Kansas, Oklahoma, North Dakota -- are now above $3.75 for regular. A month ago, they were below $3.00. SmartAsset's analysis shows California's 21.4% year-over-year increase leading the nation, but the national average itself has climbed 38% from $2.98 to $4.104 in thirty-seven days. [6] Charlie Bilello's chart of the surge, already viral at $4.06, will need updating. [7]

The structural driver has not changed. The Strait of Hormuz remains effectively closed to commercial traffic. Brent crude's physical price has detached from its futures price by more than $30. Refineries on the West Coast, which depend on Pacific Rim crude imports, face supply constraints that East Coast refineries do not. California's unique CARB-compliant fuel requirements add further isolation. The state cannot simply buy whatever diesel is cheapest on the global market. It must buy the diesel that meets its environmental standards, and the supply of that diesel has been squeezed by the same war that is squeezing everything else.

The $7.559 figure for California diesel deserves to be understood in context. The previous all-time high of $7.012, set in June 2022, lasted briefly. Prices fell as the Ukraine war's energy shock dissipated and global supply chains adjusted. That adjustment took months. The current shock is younger -- thirty-seven days old -- and the underlying cause, the Hormuz blockade, shows no sign of resolution. The April 6 Iran deadline approaches. Nothing about the diplomatic calendar suggests relief at the pump.

For most Americans, the number that matters is $4.10. It is the number they see on the sign when they pull into the station. It is the number that reshapes the budget, cancels the road trip, consolidates the errands. But for the economy that sits behind the gas station sign -- the trucks, the trains, the tractors, the ships sailing the long way around Africa -- the number that matters is $7.56. That is the number that moves the things Americans buy. And it has never been this high.

-- DARA OSEI, London