The Census Bureau uses , which are generalized representations of USPS ZIP code service areas.
Many states provide their own localized ZIP downloads for higher accuracy. For example: Download State Line zip
You can download these by state or for the entire nation from the Gazetteer Files or the Cartographic Boundary Files . The Census Bureau uses , which are generalized
This is the primary portal for searching and downloading tables in ZIP, Excel, or CSV formats. The Census Bureau uses