Treasure Revealed !!!

All I can say is “Wow!” Arline sure knew how to set up a photo shoot. I’ve been working with the negatives that fell out of The Magic Cupboard to scan a few on my flatbed scanner. When I saw this one, I was stunned. It appears to be part of a series and I can’t wait to scan and print the rest of them. Please help out, U.S. Military experts — WWI or the Mexican American War? Some of Arline’s letters from her cousin Sam talk about his Army unit getting ready for the Mexican invasion along the border states. But Arline also married a man who enlisted (or was drafted) in the Army shortly after the wedding in 1917. I’m putting the date of this photo about 1916-1917 until a better date comes up. Ideas?