Close Knit Networks in Cities

"Over time, density became a boon, economically, socially, intellectually. Living in a city became a way to encourage health. People could walk where they needed to go and support one another in tight-knit social networks."

That's from a NYTimes article on people leaving big cities.

Back in the day  the stereotype was that cities were the places where people were alone and lonely, finding solitude and privacy, enjoying anonymity.  At least that was one stereotype.  Another was cities were homes to ethnic groups (representing the last gasp of immigration before the restrictions of the 1924? act kicked in).  By the 60's the stereotype was of the black inner city ghetto.  

Perhaps it's true that for WASP migrants from the rural areas and suburbs the cities represented a freedom from small-minded prejudices and rigid social norms enforced by the community, or at least it was true enough for a sufficient number of writers for them to perpetuate the stereotype. 

Anyhow, things change.