For anyone else wondering why isn&#x27;t <i>National Five-Digit ZIP Code and Post Office Directory</i> in public domain like every other work of the US government:<p>&gt;Works by certain independent agencies, corporations and federal subsidiaries may not be considered &quot;government works&quot; and may, therefore, be copyrightable. For instance, material produced by the United States Postal Service are typically subject to normal copyright.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Copyright_status_of_work_by_the_U.S._government#Exemptions" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Copyright_status_of_work_by_th...</a>