I do not know the age. However, I was able to track down the photograph studio that framed the painting. The Studio was in Beatrice, Nebraska, USA. The owner of the studio was born in 1887 and owned the Studio until his death in 1925. After his death the studio was closed.
So, my guess the age can be estimated between 1887-1925.
I purchase the painting from a small antique shop some months ago in Neighboring Denver, Colorado USA. Many people from Nebraska relocate too Colorado to live. So, I can be quite sure it's how it arrived here.
Size: 19 1/4 x 15 5/8
Stan