In 1850 she moved with her widowed mother to Orwell, Ohio, where she attended high school and later Lake Erie Female Seminary from 1859 to 1862.

The League promoted married women's economic independence and laws requiring child support from absent fathers, as measures likely to improve public and private morality.

She was also an advocate of eugenic sterilization, backing a law allowing the procedure in cases of "promiscuous propagation of imbecility and criminality.

[5] Grannis also focused her energies within New York City, attacking the gowns worn by audiences to the Metropolitan Opera as being too revealing;[6] visiting music halls with her brother to see the immoral aspects of the popular shows for herself.

[1] Her dress reform advocacy included campaigning against corsets, and fashioning her own "rainy day costume", with shorter skirts to avoid puddles.

[8] Late in 1925, in the last months of her life, she described her work to free married women from lunatic asylums, where they had been committed by an unhappy spouse with minimal medical advice.

"[9] Grannis was a member of the First Church Disciples of Christ in New York City, until her membership was dismissed (but she was allowed to continue regular attendance and sacraments) in 1906,[10] for her being "a disturber of the peace.