Most(or a whole lot of) people in LI work in NYC...
LI counties coordinate with NYC in alot of levels for a reason, so no, they're not really THAT apart.
I disagree completely - they're worlds apart culturally. LI is full of suburbs that lack diversity, NYC is like the complete opposite of that. Geographically, sure it takes 45 minutes or so to get there but.... yeah, not a lot of cross over except the commuters that come in/out on the weekdays.