Does the motto there on the frame say ""For Liberty" ? The style of the frame and the uniform seem post-war to me. Perhaps this handsome soldier served in the Spanish American or WWI?
Just because it's been placed in an American patriotic frame doesn't necessarily mean the subject has to be American or definitely indicate when it placed there. It's a type of cap worn famously by Austrian troops in WWI and copied by the Germans in the 1930's for their own Gibergsjagers and after the Anschluss became the pattern for the famous M.1942 cap.
Yeah, definitely looks WW1-era, and I agree, I think he was on the wrong side to be in that frame, lol! My first thought was that he is wearing an Austro-Hungarian Empire uniform.
Both the cap and the jacket suggest Austro-Hangarian to me too. The two burrons on the hat, the collar on the jacket all fit that era. Possibly he left there and came to America after the war,