From 1900 to 1965 Americans were more and more sociable. That began declining in 1966 and by 1980 we saw the first fruits.
Bowling leagues and PTA membership crashed, and church membership began to stall. It’s gotten worse ever since.
Main street churches are closing. Political Party membership is declining. Marriage and family creation is declining.
That same era, we became increasingly mobile. Children going off to college, marrying someone in that same college, not going back to their home town to live, etc.
Yes. That started where I live and it started before the internet. In talking with my mother, I noticed people were very strongly bonded in her generation, something I know nothing of.
“Americans rely far less on close neighbors and venture out less often into their communitie...”
Why would we want to socialize with communists?
I was born in Western PA at the end of the 1960s, so my childhood was essentially the 1970s. First, all the houses on my block had front porches and no central air. People would sit out on their front porches after work and talk or just listen to a Pirate game on the radio in the summer. New houses just don't have front porches (generally speaking), they have back decks inside privacy fences, and they all have central AC. Both of those things can contribute to people not even knowing they have neighbors.
There was also something about having three network TV channels and PBS that also served to bring people together. When we'd go to school in the morning, kids would talk about last night's episode of Happy Days or the Six Million Dollar Man. Today, with the proliferation of online content, it's unlikely any two school kids (or coworkers for that matter) watched the same thing the night before. Even if people are fans of say, Yellowstone, or other streaming shows, they're no longer locked into watching them at the same time every week, so that in many ways eliminates just one more common thread people used to have.