food can be made in the park or in sky gardens
room to make thing can be made if you build up or if you build over roads
or hell make the city one big building if you realy need the room.
that being said Manhattan would be hit 1st and im not sure of where you would need to be to have the knowagle to be able to keep making suff(anything outside of what is normaly made in that area) if everything hit the fan...
somewhere near on of the google datacenters I would think.