South of central park, all of Manhattan is enclosed in glass, a carefully maintained habitable environment, spring 365 days a year. A glass roof is supported by the tops of smaller buildings and fills the gaps between taller ones. Cars are forbidden with the enclosure, as air pollution has nowhere to go, and much of the subway system is flooded. There is an electric bus service, bicycling is encouraged, and many streets have been converted to pedestrian only walkways and "open-air" markets.
Outside of the enclosure, things are dicier. The giant squatter cities of Brooklyn, Queens, and the Bronx. Survivors focused on getting through the day, and preparing for increasingly difficult winters. Although they hate it, much of their economy is based on the Manhattan Enclosure, either in service positions or making hand-crafted goods to sell there on weekends.