They used to include design details, even the font selection, in the original announcements for the issuance of US Postage stamps. The US Postal Service has a record of those (certainly the National Archives would have them).

Of course, they have never used fonts - metal, digital, or otherwise, although they may have used patterns. Each stamp die, including the lettering, was hand-engraved.

- Herb

Wow, thanks for the help Herb! Good to know.
Sarah