I have a query, and I'm kind of at a loss on how to frame it. I've Googled "small towns," which is far too broad a category to give me what I want, and the population of specific towns, which also works out weirdly -- I've also e-mailed friends of mine who live in what they call small towns, but haven't gotten back much in the way of answers.
How large a population does a "small town" have to have before it is plausible for a resident to not know everybody in it? For a kid, mid-teens, to see someone they don't know and not immediately assume "stranger!" Or to know people on sight, but not necessarily know their names? (I'm from New York and beyond clueless -- I do not know my neighbor two houses down.)
(Setting: I have a town that needs to be fairly isolated, enough to not be invaded very much at all, yet large enough to maintain a healthy gene pool. It's a fantasy story but I'd like to keep the fantastic to a minimum. Timeframe: Industrial Revolutionish? Residents know horseless vehicles exist but might very well have never seen one. They fish.)
ETA: Well I hate to say "my question is answered" in boldface, since I'm perfectly happy to get as many more comments and insights and tangents as you're willing to give me. But -- so much thanks to all of you. You've all given me much food for thought, even if I didn't specifically comment back. (And so quickly!) Especially the personal experiences -- can't really Google those.