Can you imagine how New York would far, even if not hit by a nuke? The resulting panic, millions trying to flee (including a large % of the police force) would result in almost immediate and widspread anarchy.
Add the EMP, fridges and water systems stops, so there would be starvation and water shortage within days, surrounding areas are overrune by refugees and quickly runs out of food.
It woukld kill a lot more than a dozen Hiroshima/Nagasaki type bombs, a death toll in the millions.