Good point; I was thinking of variance between countries, but countries aren't monolithic either. There might even be interesting variation city-to-city, or between urban/suburban/rural areas, or different socioeconomic areas.
I have the opposite second-hand report, though: a friend from California tried introducing himself to his new neighbors in Boston and basically got no response, as if introducing yourself to your neighbors was a weird thing to do. His general impression is that Bostonians tend to socialize, but grouped along very specific location/class lines, where you're a "foreigner" if you're from even as far as Somerville, let alone California.
I have the opposite second-hand report, though: a friend from California tried introducing himself to his new neighbors in Boston and basically got no response, as if introducing yourself to your neighbors was a weird thing to do. His general impression is that Bostonians tend to socialize, but grouped along very specific location/class lines, where you're a "foreigner" if you're from even as far as Somerville, let alone California.