Tannahill's paintings and fabrics can be found in the Newark Museum, Greenville County Museum of Art, Greenville, South Carolina, Zimmerli Art Museum at Rutgers University, and in many private collections. Her work is at the Bibliothèque nationale de France. A collection of her work is on display in Warrenton, at the Green-Polk-McAuslan House within the Warrenton Historic District. Tannahill, described as having been tall, blond, and striking in appearance in her youth, never married. She was a Christian Scientist who believed in suffrage for women. She lived in New York by 1914, giving her address as Van Dyck Studios at 939 Eighth Avenue. Beginning in 1916, she spent her summers in Massachusetts a tradition that she continued for 30 summers. She spent the last years of her life and died in Warrenton. She was buried in Petersburg at Blandford Cemetery. Since her death, Tannahill's work has continued to be included in exhibitions, such as "Eight Southern Women" at the Greenville County Museum of Art in 1986 and "Nine from North Carolina" in 1989 at the National Museum of Women in the Arts and in a traveling show, like the exhibit sponsored by the Fayetteville Museum of Art in North Carolina.