Is gasoline more expensive in western South Dakota vs. the eastern part of the state?

Rapid City and most places in western South Dakota have higher gasoline prices than Sioux Falls and other parts of the eastern part of the state.

Over the past 18 months, Sioux Falls’ gas prices are typically 10 cents to 20 cents below the statewide average. 

On Aug. 11, average prices in Rapid City were $3.10 per gallon and in Sioux Falls, $2.89 – a difference of 21 cents.

One year ago, Sioux Falls’ price-per-gallon was 50 cents less on average.

There are several reasons for the disparity. The Sioux Falls market is more competitive, there’s a major pipeline feeding Sioux Falls and the fuel comes from different regions, according to an expert from Gas Buddy.

Gas prices can vary even more wildly from state to state because of the differences in state taxes. Federal and state taxes make up about 15% of the cost of a gallon.