[2] For three years, Rathbun worked on a voluntary basis for her brother, before being granted a clerkship by Spencer Fullerton Baird at the Smithsonian Institution.

[2] After 28 years of working at the museum, Rathbun was promoted to assistant curator in charge of the Division of Crustacea.

[2] Rathbun's first publication was co-written with James Everard Benedict and concerned the genus Panopeus; it was published in 1891.

[2] Her largest work was Les crabes d'eau douce ('Freshwater Crabs'), which was originally intended as a single publication, but was eventually published in three volumes between 1904 and 1906.

[2] She wrote or cowrote 166 papers in total, including descriptions of 1147 new species and subspecies, 63 new genera, one subfamily, 3 families and a superfamily, as well as other nomenclatural novelties.