Why are there no ZIP Codes in the Geographic Names Information System (GNIS) Database?
The GNIS contains named communities, both incorporated and unincorporated, but these communities do not necessarily correspond to ZIP Code areas. ZIP Codes are unofficial entities developed and maintained by the U.S. Postal Service solely for the purpose of delivering mail. It is not within the mission, purpose, or resources of the GNIS to maintain ZIP Code information.
ZIP Code areas are named (unless there is duplication) for the most prominent community in it or which it serves. Numerous ZIP Code areas contain multiple named communities within them, particularly in rural areas, and in urban regions, single large communities encompass multiple ZIP Codes. ZIP Code and community boundaries frequently do not correspond or correspond only roughly. Also, many communities for which the ZIP Code area is named are not incorporated, which means they do not have legal boundaries.
Therefore, the ZIP Code boundary in no way indicates a legal "footprint" of a named community, is not official for purposes other than delivering mail, and changes periodically. For additional information concerning ZIP codes, please contact the Postal Service.