I'm also from a small rural area where I went to school with the same kids K-12. I'm still in social media contact with 25-30 - and by that I mean not just reading posts or glancing at pictures, but commenting, asking questions, sharing something you know they'd like, actively following (and then there's another larger group where we are just social media connections, without interaction). Without social media, the number would be more like 2-3. My family moved away from my small town as I was finishing college, so in person connection would have been difficult to keep, but if my parents still lived there I'd probably see 10-12 people at least once a year, and enjoy catching up.
Conversely, we have not had a reunion from high school in a long while. I think social media makes that sort of reunion not as necessary.