From Martha's autobiographical manuscript, "Memories: Grave and Gay," Chapters 23 and 24:
After graduating from Smith College, Edith returned to Chicago, tutored private pupils for a time and then started working for the publisher A. C. McClurg & Company, "making their catalogs, and reviewing books for their large annual catalog. She spent two years making 'Granger's Index to Poetry and Recitations,' called 'A Monumental Work.' "
Edith remained with A. C. McClurg & Co. until October, 1897, when she went to New York to accept a position (I have yet to confirm what her position was but my educated guess is that she was possibly working for Harper Brothers in New York). By June 1898, she gave up her position (according to her mother, she didn't like living in New York). After returning home, she worked in the Chicago office of Harper Brothers for a year, and then was back again with A. C. McClurg and Co., until she and her mother left for California in 1906.