Which states are the most energy-cost efficient for drivers? That depends, of course, on whether a motorist is operating a traditional gasoline-powered vehicle or an electric vehicle. Which means there are multiple answers to that question of vehicle energy-cost effectiveness, and the answers can and do change each month.

ChooseEnergy.com’s Driving Fuel Costs by State page monitors monthly costs to show you the latest statistics, trends and analysis of the costs to drive traditional vehicles and electric ones. Choose Energy analysts crunch numbers provided by AAA, the Department of Energy and other sources to measure differences by state.

Let’s start with gasoline. As of Sept. 1, drivers in the U.S. paid an average of $2.23 per gallon for regular gasoline, according to AAA. That was 36 cents less per gallon than on Jan. 1.

Which states had the most and least expensive gasoline?

Drivers in California paid the most for their gasoline on Sept. 1 – $3.24 per gallon. That was 1.9 percent more than they paid one month earlier but still 45.3 percent more than the national average. Drivers in Louisiana and Texas paid the least per gallon on Sept. 1 – $1.91.