We drive the Toronto through to Florida route every year via 77/95/ etc.

We have had luck with Shell stations through most of the route. The odd time you'll get one that doesn't accept.

BP generally never accepts cdn cards at the pump.

We've only ever found one Shell station in Georgia that accepts at the pump.

In Florida we signed up for Racetrack pay inside card which when swiped allows us to fill up and pay inside after the fact.

Not sure if this is reflective across the board but we have had far more luck with Shell than any other chain.

We could however use our cards throughout Europe at the pump. (thank you chip and pin)