Although she achieved a certain degree of critical acclaim for several of her novels, short stories and some of her journalism career during the 1920s, 1930s and 1940s, she faded from public literary view in the later part of her life.

She turned out several pamphlets on early Minnesota history for the Great Northern Railway, which was then based in St. Paul, and a trip to Africa in 1927 provided fruitful material for a travel book, Then I Saw the Congo, as well as a collection of stories, Under the Sun.

As a travel writer, Flandrau was ahead of her time, exploring her exotic locale from an objective, humanistic standpoint, and challenging the notion that Europeans were the superior race.

Flandrau was the sister-in-law and close friend of architect Theodate Pope Riddle, who provided her with a life tenancy in a house on the Hill-Stead estate in Farmington, Connecticut.

In her will, she left a major bequest to establish, in honor of her brother-in-law, another noted author, the Charles Macomb Flandrau Fund at Harvard University, aimed to encourage good writing.