Diesel and fuel tax by state

The Energy Information Administration publishes a weekly on-highway diesel price for ten districts, not for fifty states. There is no state-level diesel price to publish, for any state, from any source.

So every US site with a "state diesel price" page is serving you a district number under a state heading. Some say so in a footnote. Most do not say so at all.

This table gives you the two things that genuinely are per-state, the fuel tax a state levies and the tax a carrier files under IFTA, and names the district each state's diesel figure comes from. A state page shows the same district number a neighbouring state's page shows, and tells you that is what it is doing.