This photograph from the Alice Wilcox Collection is a tintype measuring 2.5" x 3.5" which has no accompanying paper mat and no identification. Tintypes were popular in the 1860s and 1870s but continued to be used into the 2oth century. I'm not a fashion expert and maybe someone else can do a better job of dating this photo by the clothing these two women are wearing, but I'm thinking it's much later than the 1870s... maybe the 1910s? I would guess the women are about college age.
Most of the people in this collection of photographs seem to be from Illinois or Wisconsin. Reader, if you recognize the people in this picture, please leave a comment or, better yet, use my Contact form to open a private email discussion on the subject.