Washington's gas price gap over the U.S. average, by part, 2015-2026

What this dataset measures

EIA's weekly survey is the only government series that measures Washington and U.S. average pump prices the same way every week, and EIA's twice-yearly tax table is the standard source for state gas taxes. The carbon-market estimate comes from FactHub's published comparison of Washington with the U.S. average before and after the market began, which tracks the allowance auction price quarter by quarter.

Geography

Washington, United States

Unit of observation

Year

Update cadence

Yearly, after EIA publishes the July tax table and the year's weekly prices

Curator

FactHub Research Team

Saved analyses

Derived from

This dataset uses data from these FactHub dataset versions.

• Washington Gasoline Price Premium and Carbon Allowance Costs, 2015-2026 Version 2

  Carbon-market estimate per year (difference-in-differences vs U.S. average) and CPI factors.

Sources

1. U.S. Energy Information Administration, Weekly Retail Gasoline Prices, regular all formulations: Washington (EMM_EPMR_PTE_SWA_DPG) and U.S. (EMM_EPMR_PTE_NUS_DPG) Weekly Washington and U.S. average retail prices of regular gasoline, all taxes included, 2015-2026.

   Retrieved November 8, 2026. Public domain (U.S. government work). Allowed; EIA asks to be cited.

   Reliability: Government. EIA samples retail outlets at 8 a.m. each Monday; prices include all taxes.

2. U.S. Energy Information Administration, Federal and state motor fuels taxes (fueltaxes.xlsx), sheets January 2015 through July 2026 (revised) Washington's total state gasoline taxes and fees and EIA's average of the states, January 1 and July 1 of each year.

   Retrieved November 2, 2026. Public domain (U.S. government work). Allowed; EIA asks to be cited.

   Reliability: Government. Compiled by EIA twice a year from state statutes and agencies. Excludes county and local taxes.

License: FactHub's selection, cleaning and combined tables are licensed under CC BY 4.0. Source data keeps the terms listed above (terms).

Limitations and reproducibility

Reproducible: wa_minus_us_cents is the mean over each year's weeks of EIA's Washington weekly regular price minus its U.S. weekly price. state_tax_gap_cents is the mean of (Washington total state taxes and fees minus EIA's average state) on January 1 and July 1. carbon_market_cents is FactHub's difference-in-differences effect against the U.S. average for that year, in January 2024 dollars, divided by that year's CPI-U factor to January 2024. everything_else_cents = wa_minus_us_cents - state_tax_gap_cents - carbon_market_cents.

• The carbon-market part is an estimate: the rise in Washington's gap over the U.S. average since 2023, beyond its 2015-2022 level, after removing gas-tax changes (FactHub dataset wa-cca-gasoline-price-premium-2015-2026, version 2). It also picks up anything else specific to Washington that changed in 2023, such as the Clean Fuel Standard, whose cost Ecology estimates at under 1 cent a gallon. Other estimates range from 7-24 cents (Ecology's contracted study, 2024) to about 52 cents (full pass-through of the June 2026 auction price).
• Everything else is what is left after the two other parts: West Coast crude, refining and shipping costs, refinery and pipeline outages, station costs and margins, and local taxes. Washington publishes no refiner or retailer margin data, and EIA stopped publishing state wholesale prices in 2022, so this part cannot be split further.
• The state-tax part is the gas tax. On July 1, 2026 Washington's state gas tax was 56.5 cents a gallon against an average state's 28.7 cents (27.8 cents more), while its other state taxes and fees on gasoline (mostly the 3.55-cent hazardous substance tax, plus about 0.1 cent of oil-spill taxes) came to 3.7 cents against the average state's 5.8 cents (2.1 cents less; several states count a sales tax on gas there, and Washington has none). EIA's table leaves out Washington's petroleum products tax (0.3% of wholesale value, roughly 0.7 cents), which falls in everything else.
• The U.S. average state tax is EIA's simple average of the states, not weighted by gallons sold. Each year's tax gap averages EIA's January 1 and July 1 readings.
• 2026 covers January 5 to November 2. From March 2026 the Iran war and the closure of the Strait of Hormuz raised prices across the country; Washington's gap was about 95 cents in January-February and $1.10 after.
• Prices are in dollars of each year, not adjusted for inflation.