I saw no shortage of resolve in NYC after 9/11. Just as untog said of London, we all went to work the next day and carried on with our lives.
But that is just me making up a hypothesis that fits the data in retrospect. Maybe something else is going on.
I don't remember much about NYCs reaction, as I was in school in Atlanta at the time. But my father worked on an air force base at the time and reactions there and around that town were anything but carrying on.