[jonfromsf]

These were a huge part of the American social fabric in the past. Most of the organizations are still active, although smaller than before. There's Freemasons, The Elks, Rotary International, American Legion, VFW, Knights of Columbus, Loyal order of Moose, Shriners, Lions Club, Kiwanis ...

[ngc248]

Also, as compared to before, the amount of solitary activities one can do have increased a lot. This has also led to these asspciations becoming smaller.

[kelnos]

I do wonder what percentage of people (men, in particular, I guess) are members of such organizations. I'm pretty sure I don't even know one person who is a member. I certainly have my own bubble, though, so I assume they're still decently active, but my general impression is that it's likely, say, under 5% of the US population that belongs to one of those.