The digital equivalent of those places are Facebook groups. meetup.com, although their mobile redesign is a complete joke.
Linked in groups. In the UK we have gumtree, probably Craigslist in the US. There's probably more, just sounds like you never looked.
You're looking for digital bulletin boards for your area, groups need new blood as much as you want to find them, you've just got to look.
Plus, of course, the local college night classes.
I just searched meetup for my costal corner of a home town of 20k in the UK and it had a bunch of meetups nearby, so it's pretty easy to find stuff.