here. Judging from her dress, the year must be around 1890. However the website notes her first husband's parents married in 1888. I know it took a while for fashions to travel "out west" but it is hard to imagine that this very fashionable lady posed for her portrait wearing that gown after 1900.
All that said, isn't she lovely?
Header: Lottie Campbell, photograph date unknown, via A Harlot's Progress