Alois Fabry was an artist, educator, and author. He painted two of the largest WPA-commissioned murals, covering over 1,800 square feet of the Brooklyn Borough Hall rotunda. Alas, their fate is unknown. You can read all about it here.
The work that inspired this card can be seen at the website for the Smithsonian American Art Museum.
Fabry painted two post office murals: Floating Horses Down the Cumberland River (Williamsburg, Kentucky) and The Mail (Upper Sandusky, Ohio).