This pump organ must date back to the early 1900's, or even
the 1890's. I cannot distinguish the manufacturer from the
plate inside the organ, it seems like "Merduith Organ Company,
Chicago". However, my searches to locate an organ company by that
name was fruitless, so far.
There were several Chicago organ companies in the 1890's, and
they did ship, by horse-drawn wagon, to several western frontier
states.
The one music book on top of the organ, is named:
"Triumphant service songs".

*the afrikaans name by which these pump organs were known when i
was growing up