Diesel prices along
I-90.
I-90 runs west to east from Seattle to Boston, crossing 13 states. Right now the cheapest median on the corridor is $5.60/gal in Montana and the most expensive is $7.00/gal in Washington, a $1.40/gal gap.
Data window: last 7 days · 3,175 observations · 1,964 truck stops on I-90
Where the cheap stops fall
Fuel in Montana, state 3 of 13 running west to east.
Running I-90 west to east, Montana is where the median drops lowest. A 250-gallon fill there runs about $350 less than the same fill in Washington, on one truck, on one fill, before any negotiated discount is applied. The single cheapest stations on the corridor are in South Dakota, where the cheapest 10% post $5.35 or less.
State medians tell you which state to lean on. Which station, how many gallons, and whether the tank can make it there is what ValveRide Flow works out per dispatch, with your contract rates and state fuel-tax differences layered on top of the posted price.
State by state
I-90 diesel prices, Washington to Massachusetts
States in road order, west to east. Cheap and expensive are the 10th and 90th percentile of tracked stations in each state; spread is the gap between them, and a wider spread means more room for a routed fleet to save inside that state.
| # | State | Cheap (p10) | Median | Expensive (p90) | Spread | Stations |
|---|---|---|---|---|---|---|
| 1 | WashingtonWA | $6.55 | $7.00 | $7.30 | $0.74 | 57 |
| 2 | IdahoID | $5.60 | $6.16 | $6.26 | $0.66 | 63 |
| 3 | MontanaMTcheapest median | $5.40 | $5.60 | $5.80 | $0.41 | 56 |
| 4 | WyomingWY | $5.40 | $5.96 | $6.09 | $0.69 | 64 |
| 5 | South DakotaSD | $5.35 | $5.66 | $6.20 | $0.85 | 59 |
| 6 | MinnesotaMN | $5.70 | $5.89 | $6.10 | $0.40 | 167 |
| 7 | WisconsinWI | $5.60 | $5.80 | $6.00 | $0.40 | 297 |
| 8 | IllinoisIL | $5.80 | $6.10 | $6.30 | $0.50 | 340 |
| 9 | IndianaIN | $5.76 | $6.00 | $6.20 | $0.44 | 206 |
| 10 | OhioOH | $5.60 | $6.00 | $6.16 | $0.56 | 278 |
| 11 | PennsylvaniaPA | $6.00 | $6.30 | $6.70 | $0.70 | 219 |
| 12 | New YorkNY | $5.66 | $6.00 | $6.50 | $0.84 | 113 |
| 13 | MassachusettsMA | $5.75 | $6.00 | $6.30 | $0.55 | 45 |
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Questions, answered
I-90 diesel prices, explained.
Where is diesel cheapest along I-90 right now?
The lowest median diesel price on I-90 is $5.60 per gallon in Montana, across 56 tracked truck stops. The cheapest 10% of stations anywhere on the corridor are at or below $5.35/gal, in South Dakota.
Which states on I-90 have the most expensive diesel?
Washington has the highest median on I-90 at $7.00/gal, $1.40 above Montana. On a 250-gallon fill that gap is about $350 between the two states, before any negotiated discount.
How much does diesel cost along I-90 today?
State medians along I-90 currently range from $5.60 in Montana to $7.00 in Washington, based on 3,175 price observations from 1,964 truck stops in the last 7 days. Prices are pump-posted retail, not contract rates.
Prices are pump-posted retail percentiles from tracked truck stops in the 48 contiguous states, never contract or discounted rates. Methodology and the full state table live on the national diesel prices page.
Connecting corridors
Other interstates that share a state with I-90
All corridors: diesel prices by interstate. Origin-to-destination view: diesel prices by lane.
Your trucks run I-90.
Flow makes every fill count.
Live prices, your negotiated contracts, and state fuel-tax math, applied automatically on every dispatch, with every claimed dollar reconciled against a real transaction.