In the upper mid west (Dakotas) the price of gasoline for regular unleaded is $2.75 gallon. There are no refineries within thousands of miles of the Dakotas.
Here in the San Francisco Bay Area the price of gasoline is over $4.00 per gallon, unless you purchase your gas at Costco, it is well under $4.00 per gallon. We have multiple refineries here in the Bay Area.
Cost to transport gas to stations in the Bay Area is minimal compared to the cost to transport gas to stations in the Dakotas. What is the cause for this location cost and price? Maybe it is Bakken oil fields in the Dakotas and Canada! But that resource is transported to the Bay Area.