Both married and single women operated early photo studios. If the CDV's in my collection are representative, there were more married women photographers than single.
Below are two examples of the work of Mrs. H.P. Harvey of Maquoketa, Iowa. The upper corners were clipped to fit into an album.
Mrs. John H. Oleson of Minneapolis was the photographer of these two portraits. The style of the lapels on the jackets suggests 1880's.
Photos by Mrs. R.A. Smith of Carlisle, Pennsylvania (left) and Mrs. Van Housen of Hammondport, New York. Both photographers used similar fringed posing chairs, plain backdrops and patterned floors.