This postcard is an example of a Real Photo Postcard (or RPPC). Real Photo Postcards are produced by a photographic, rather than a printing, process and are continuous-tone photographic images printed on postcard stock.
The term recognizes a distinction between the real photo process and the lithographic or offset printing processes employed in the manufacture of most postcard images. The publication of Real Photo Postcards began around 1901-1903. Each individual Real Photo Postcard is more expensive to produce than an individual pictorial postcard but they are not mass-produced in large quantities.
RPPCs could be produced in much smaller quantities, even just a quantity of one, and they are therefore more prized by collectors because they tend to show one time happenings such as fires, floods, tornadoes, train wrecks, lynchings and other “disasters”…and eclipses.
This RPPC was produced on AZO paper, a Kodak paper which was produced between 1904 and 1918. AZO paper was a very popular paper. It was what is called a “printing out” paper which meant it could be printed out in sunlight (you didn’t need a darkroom), it was contact printed so you didn’t need an enlarger or other fancy equipment, and it was a slow paper so it allowed for error in printing out. You didn’t need to burn in or dodge the photo like later photographers had to do. AZO paper became very popular with amateur photographers.