Let's hear it for NYC, people are actually nice!!
What a surprise.
I've noticed people will talk to you ANYWHERE if you give off vibes of being approachable. I get talked to all the time. It's little encounters like in the supermarket, commenting on prices or lines or at an event.
Walk a dog and many people WILL talk to you anywhere.
When I lived in the UK, one day I was at a news agents/corner store with my son who was still in a carriage/pushchair this old man started talking to me like he knew me.
It was a small town, so maybe it got out a few Yanks lived there and someone who actually LIKES Americans decided to be friendly. I don't know.