Please follow https://jfk.blogs.archives.gov/2021/07/01/papers-of-h-bentley-hahn-the-man-who-invented-the-5-digit-zip-code/.

Please follow https://jfk.blogs.archives.gov/2021/07/01/papers-of-h-bentley-hahn-the-man-who-invented-the-5-digit-zip-code/.