Most people watch gas prices at the pump and stop there. That's the wrong number to be watching if you want to see inflation coming before it shows up on a grocery receipt.

Diesel is the fuel that actually moves the economy. Trucks hauling goods across the country run on it. Trains do. Farm equipment planting and harvesting food does. Construction machinery, generators, industrial equipment — nearly everything that produces or transports a physical good depends on diesel somewhere in the chain.

When diesel prices rise, that cost doesn't stay with the trucking company. It moves into the cost of shipping, which moves into the cost of the product, which moves into the price on the shelf, by the time it reaches you. Energy costs don't just affect your fuel tank. They quietly embed themselves into the price of almost everything you buy, weeks or months before you notice the actual number changing.

This is the chain worth watching: energy disruption raises transportation costs, transportation raises the cost of nearly everything, and that compounds into the inflation people eventually feel at the register, in rent, in every basic necessity. By the time it's obvious, it's already been moving for months.

Watching gas at the pump tells you what you're paying today. Watching diesel and energy more broadly tells you what everything else is about to cost.