I live in NC one mile from the SC border.
I ALWAYS go directly across the SC border to the first gas station to take advantage of the 20+ cents difference in the cost between NC vs SC. All of it is state tax.
One mile north of my house, in NC, the price now is $3.67.
Go one mile south and its $3.42.
Even if I am very low while driving around Gastonia, NC I only get a few dollares worth to last me until I can whip it across the state line into Clover, SC.
Ye olde Clover where I grew up and still visit. Haven’t been in Gastonia in long time.