Tyler Cowen links to a study that asserts that, counter to the American Beauty/John Cheever view, living in the suburbs can enhance your social life and yield more and deeper friendships. According to a news story about it,
The study, released by the University of California at Irvine, found that for every 10 per cent decrease in population density, the chances of people talking to their neighbours weekly increases by 10 per cent, and the likelihood they belong to hobby-based clubs jumps by 15 percent. "We found that interaction goes down as population density goes up. So, turning it around, it says that interaction is higher where densities are lower," says Jan Brueckner, an economics professor at UC Irvine who led the study. "What that means is suburban living promotes more interaction than living in the central city."
I'm not sure that last bit of logical jujitsu is all that useful, but my empirical observations of living in New York City, where the density is fairly high, bears out the idea that interaction decreases with density -- other people are simply too numerous to be acknolwedged, and too likely to be strange (from some totally unknown origin, with some utterly unexpected agenda). One naturally raises one's guard against the people who press against you, and for better or worse, one derives methods to assess people by their looks and use those judgments to insulate oneself. Where density is lower, the population is more homogenous and the interactions occur in more mangable numbers and at more managable intervals so that one is willing to make oneself present for them.
I suppose it makes sense the hobby-group joining behavior would be higher in the suburbs as well, because special effort must be taken to join things in order to particpate in social life -- otherwise you can remain isolated in one's private household, sealed off from neighbors by yards and cars and all the rest of the infrastructure of the atomized nuclear family. Whereas in a dense city, a walk down a street is enough to evoke that feeling of social connection. (To paraphrase Nigel Tufnel, "Too much fucking connection".) The very obviousness of how our choices impact one another -- the pressures other people's decisions put on you -- in a city may make us balk at social activity, dream of withdrawal, dream of passing a day without other people dictacting so much of how we might feel, or worrying about how what we do inevitably afflicts others. The pressure to conform, be different, be in fashion, be considerate, be aware of what you are doing, etc. -- all these are palpably acute in the city, and we are routinely confronted with our choices yielding disappointing outcomes due to the presence of so many others making similar decisions. (You can tell I've been reading about game theory, I guess.) In the suburbs, where the communities are planned to mask that (and thus encourage us in a naive faith in the sovreignty of individual choice) we believe we can choose the terms on which we interact and are affected by others, and this likely plays out in voluntary associations that are organized around hobbies. (Not sure though how this meshes with Putnam's findings in Bowling Alone -- it seems unlikely that he could have been so far off.)