As of September 2015, South Carolina, New Jersey and Mississippi are the states with the lowest average gasoline prices, and California, Alaska and Nevada have the highest average price per gallon. The cities of Spartanburg, South Carolina, Lubbock, Texas, and Chattanooga, Tennessee have lower average gas prices than any state as a whole. Las Vegas, Nevada, and many individual cities in California such as Los Angeles and San Francisco have higher average gas prices than any individual state.
One factor that creates variation in fuel prices from state to state is taxes. In some states, taxes account for 15 percent or more of the price per gallon. In Pennsylvania, for example, 21 percent of the gas price goes to the state. In eight states, gasoline taxes make up less than 10 percent of the retail price. In addition, not every state calculates their tax in the same manner. In some states the tax is a flat fee. In other states the fuel tax is linked to the price of gasoline, so as gas prices fall, revenues fall.
The market forces of supply and demand also affect gas prices. The Southeast United States, for example, typically has the nation's least expensive gas because it is near major refineries with access to domestic crude oil. California traditionally has higher gas prices because its refineries run near maximum capacity to meet the demand for the legally required state-specific blend of gasoline.