Again a US centric article. While it would have been impossible to achieve such, consistently, in the suburbs of US, in a city like Chicago greeting neighbors became a little more feasible, but to Mr Rogers' point - probably useless beyond four or five. In French cities like Montpellier, Aix-en-Provence, Nice, Vic-sur-Cere, etc., though, it is possible to go way over the "6 limit", with increasing benefits. I know a lot of people on the street where I live for the moment, and some of the neighboring ones, and I greet a lot of folks while walking outside ("walk" = keyword). I also greet my favorite two butchers, two or three boulangers, the fromager and a lot of folks at the farmers markets and small deli stores, cofee shops, etc., on a daily basis. The more - the better it makes you feel.
Where I live, you hardly meet more than one neighbour at random in the winter. In contrast, in villages in the south of Spain, you meet neighbors and family all day long, to the point where it gets tiring. I imagine there are many more places like that in the world. It's definitely not a universal study.
