Band in the stands
Click here to view it larger.
This real photo postcard has no information beyond the paper manufacturer’s markings (AZO, four triangles pointing up), which date it to 1904-1918. So it’s up to us to guess who these people are, where they are, and what the occasion is. This doesn’t seem to be a formally posed moment, more like a test shot before the photographer said “Okay, smile!”, or even something like a photo taken for the local paper. But the candidness almost reveals more about the personalities and relationships than if they were all smiling stiffly and properly. I wonder if the band intends to play while seated there, with all those people crowded around them. Whoever these people are, it’s a fun group of faces to examine.
Pics of Then 
Judging mostly by the hats, I’m going to tentatively date this c. 1917 (https://witness2fashion.wordpress.com/tag/ladies-womens-hats-to-make-1917/). [note: okay, now I see that you posted some info about the time window! well, that makes me more confident in my guess; at least it’s not too late.] I sure wish I knew where it was taken! does it feel like the southwest?
I would have guessed closer to the end of that time window, too, so thank you for the evidence in the link. Somehow it has a Midwest feel to me (assuming it’s even in the US to begin with), though I really don’t know. A tree expert might help, but that’s assuming the trees are native to that location. The band members and the two women furthest upper right (not sure if they’re in the band or just with the band) seem to be wearing matching neckerchiefs. They are clearest on the two men down right in front of the tuba, but I’m not seeing any logos or insignia that I can identify.