South Dakota Gas Prices and Why They Are What They Are
Prices as of July 21, 2026, per AAA · Updated July 21, 2026
As of July 21, 2026, regular gasoline in South Dakota averages $3.92/gallon (the 24th-lowest in the U.S.), per AAA — 0.08 below the national average of $4.00. Diesel averages $4.72. State fuel taxes and fees add 30.0¢/gallon on top of the 18.4¢ federal excise.
Where the $3.92 goes
| Component | $/gallon | Share | Source |
|---|---|---|---|
| Crude oil (national cost, WTI June 2026) | 2.02 | 51% | EIA |
| Federal + South Dakota fuel taxes (18.4¢ + 30.0¢) | 0.48 | 12% | Tax Foundation |
| Refining, distribution, margins & embedded program costs (residual) | 1.42 | 36% | computed |
Crude oil costs every state's refiners roughly the same, so South Dakota's position comes from the tax line and the residual: refining capacity and logistics, fuel-specification requirements, and any carbon or clean-fuel program costs embedded in the pump price.
State policies that show up at the pump
| Policy | Detail |
|---|---|
| Carbon program on motor fuel | No |
| State-specific fuel blend | No |
State government control
| Control today | Unified Republican (Governor + House + Senate, all R) |
| Years of unified Democratic control, 2001–2025 | 0 |
| Years of unified Republican control | 25 |
| Years of divided government | 0 |
Fuel-tax levels and fuel-specification programs are set by legislatures and governors; the national comparison shows average prices and taxes grouped by state control.
Compare: all states ranked · South Dakota electricity rates · gasoline prices by country
Sources: AAA (pump prices, updated daily; the industry-standard 50-state series), Tax Foundation (2026 state fuel taxes), EIA (WTI crude). The residual is computed, not reported. See methodology.