Yda Hillis Addis (born 1857,[a] disappeared 1902 in California, U.S.) was the first American writer to translate ancient Mexican oral stories and histories into English, some of which she submitted to San Francisco-based newspaper The Argonaut.

[2] Addis was born in 1857 in Leavenworth, Kansas,[2] and moved with her family to Chihuahua, Mexico, at the start of the American Civil War.

[1] The daughter of an itinerant photographer, Alfred Shea Addis, she roamed the Western frontier and Mexican wilderness, into indigenous villages, miners' camps, and other locations, mostly in Mexico and California, assisting her father.

In 1880 Addis submitted her stories of heroines, such as Poetic Justice and Señorita Santos, to The Argonaut,[1] a bi-monthly San Francisco journal founded by Frank M. Pixley.

[citation needed] Pixley introduced Addis to his good friend John G. Downey, a former governor of California, in his late sixties.

[3] Before the trial date, Addis left San Francisco for Mexico City to write for the bilingual newspaper Two Republics, owned by J. Magtella Clark.

[16] While it was long assumed that Addis disappeared in 1901, with some sources claiming she was committed by Storke to an asylum, from which she escaped, research by Ashley C. Short suggests that Addis reinvented herself as Adelayda Hillis Jackson, taking a name from her mother's family and that of her purported second husband Grant Jackson while tacking on "Yda" to her new first name, and spent nearly thirty years in Texas (after perhaps living in San Francisco and México).

Mainly residing in San Antonio, Adelayda Hillis Jackson spent the last decade of her life committed in the state hospital in that city and died in 1941.