Our gasoline tax is about 40 cents/gal less--so that's 2.50 for PA, just accounting for difference in state taxes.
Then again, we're not far from refineries here north of Houston, so transportation to market is less. That makes some cents lower in price make sense. (And that sentence is so horrible I'm not going to fix it.) Note this it was a large grocery store that's part of a chain that tries to source things in TX, not a franchisee or big name oil company. It's also not near a freeway, much less an interstate.
In fact, they tend to have a variety of sources and shop around to try to drive bargains, when possible. And given no great gasoline shortage, they tend to have very reasonable prices for gasoline. That big ol' sign gets people in (the store brands aren't bad, actually.)
The gas stations near where I live are right off I-45, with lots of exit and entrance ramps, plus a lot of population. Their prices are 2.45 and 2.50. Boost those for Pennsy taxes and distance, I could see $3.
The only gas price info I can find for anything remotely "boonies" in PA is Northumberland, was reported yesterday at 2.57. Don't know the area, I'm okay with the extreme NW (Eerie, Allegheny N.F,), the SE (Harrisburg over to Philly up through Wilkes-Barre and through the Water Gap), been to Pittsburgh, but central PA ... like a foreign country to me. So I don't know what's up with population or main roads. (Then again, I consider that to be about 150 miles east, maybe ESE, of "true boonies, PA"
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