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’m in Georgia and if you ask for tea you usually get asked “sweet or unsweet”.
Midwest is generally this way too, but some only have sweet tea.