Gas Price Differentials

What is the deal with gas prices in Indiana? We continue to be above the national average price for a gallon of gas. I am confused as to why this is. I mean, it is not like we live in a major metropolitan area. Now, I don't know how all the state taxes work for gas, but last Friday we left after work to go and visit family in Iowa. We got gas here for $3.95/gallon before leaving town. When we arrived in Clinton, Iowa 5.5 hours later, gas was $3.58. Now, approx $0.40/gallon difference is a lot of more!!. What the heck!?! I just don't get it. Todd chalks it up to regional pricing, but aren't Indiana and Iowa both considered Midwestern states? The only thing that provides any logic is that there is more corn grown in Iowa. They have more ethanol plants and many stations carry E-85 or gas with a higher ethanol content. Since we, the tax payers, are currently subsidizing the cost of ethanol, maybe this is driving the price down in that location? If so, can we get some of that here!?!