In the South East, they bring you sweetened (usually far too sweetened for my tastes) iced tea. This is amazingly universal.
I live in NC and have been probing the border for years.
For “nicer” restaurants, the universal sweet tea boundary seems to be precisely at the NC/VA border.
I knew someone back in college that tried to outline the sweet tea line. They found there’s a zone of ambiguity where it will vary from restaurant to restaurant.
I thought a good follow up would be to ask different individuals how to make sweet tea. Those who know, know you can’t just put sugar into iced tea.