Hillbillies are generally a specific type of non urban. Here in Appalachia we refer to them as off the mountain. You don’t just run into hillbillies. You have to go where they go.
The rest of us are rednecks. I don’t think redneck is “everyone south and rural” but it’s pretty close.
This is why the baby stage is so fun and the teenage stage is so damn annoying.