Key keywords: US gas price variation, state-level fuel cost, gas tax by state, oil refinery capacity, regional fuel supply, seasonal gas demand, energy policy impact, gasoline blend requirements. If you’ve ever driven across state lines and noticed dramatic differences in gas prices, you’re not imagining the gap: 2024 data from the U.S. Energy Information Administration shows per-gallon regular gasoline prices can vary by as much as $2 between the cheapest and most expensive U.S. states, and multiple interconnected factors drive these discrepancies. The first and most widely cited factor is state-level fuel tax policy. On top of the 18.4 cent per gallon federal gas tax, every state imposes its own additional tax, plus many local governments add county or municipal fuel levies. For example, Pennsylvania’s combined state and average local gas tax tops 58 cents per gallon, the highest in the nation, while Alaska’s total state and local tax adds just under 15 cents per gallon, the lowest. In high-tax states like California, taxes alone account for nearly 70 cents of the per-gallon price, compared to less than 30 cents in low-tax states like Texas. Next, regional refinery capacity and fuel supply chains play a major role. More than half of U.S. refinery capacity is concentrated along the Gulf Coast, so states near this hub, including Texas, Louisiana, and Oklahoma, have far lower transportation costs for fuel, while states far from refineries or major pipelines pay steep shipping premiums. Hawaii, which imports 100% of its fuel via ocean tanker, consistently has the highest average gas prices in the country, often $1 or more above the national average. Refinery maintenance shutdowns or unplanned outages in a region can also send local prices spiking overnight: a 2024 2-week maintenance period at two major Northern California refineries pushed state gas prices up 45 cents per gallon in less than 10 days. Special regional gasoline blend requirements also widen price gaps. More than a dozen states, mostly on the West Coast and in the Northeast, require low-emission, smog-reducing fuel blends to meet air quality standards, especially during the summer months when smog risk is highest. These specialized blends can only be produced at a small number of refineries, adding 20 to 50 cents per gallon to the cost of fuel in states that mandate them. Seasonal demand also amplifies gaps: during summer travel season, demand spikes in popular tourist states like Florida and Colorado, pushing local prices 10 to 20 cents above neighboring states with lower seasonal demand. State energy policies, such as biofuel blending mandates or temporary fuel tax holidays, can also create short-term or long-term price differences between adjacent states.