The New York City Population Division serves as New York City government's hub of demographic expertise. It is responsible for the compilation, analysis, and dissemination of census and related federal, state, and local data for city agencies, local communities, and the media. Within the department, the Population Division provides data for local and citywide planning studies, environmental review analyses, and capital planning strategies. In addition, the division provides other city agencies with data to address questions of concern involving needs assessment, program planning and targeting, and policy formulation. This includes the development of population estimates and projections for infrastructure and capital planning, such as projections for OneNYC, the long-term sustainability plan for New York City. The division works closely with the Census Bureau in an advisory capacity on the methods of data collection and dissemination for the decennial census and other federal surveys.
Why use census tracts? Census tracts are polygons and cover a well-defined geographic area. They provide more granularity (73,000 areas) than ZIP Codes (43,000) and are non-changing static geography from decennial census to census. Census tracts have a large and richer set of associated, more reliable demographic-economic data.
The U.S. Postal Service does not define ZIP Code boundaries. They exist only where U.S. mail service is provided. The population of a single ZIP code can exceed 100,000. ZIP codes may change at any time; new ZIP codes may be created or eliminated at any time. However, ZIP codes provide an easier and more comfortable way to associate or characterize demographic-economic conditions. We usually know our zip code and maybe a few others as well.