@CatsOfYore Glass plate negatives tend to be mostly from the 1910s, in my experience. Although they could be from a wider range than that, I can't say for sure.
@TheManyVoices interesting! That reminds me of one thing Ancestry's AI analyzing tool is actually good at: telling you when a certain technique and style of photography was in fashion, and therefore helping narrowing down the time a picture was taking. @CatsOfYore