[1][2] A 2013 medical study concluded that viral encephalitis actually disrupted her eyesight, based on evidence from first-hand accounts and newspaper reports of her illness, as well as relevant school registries, and epidemiologic data on blindness and infectious diseases.

The historical record doesn't show why Ingalls did not attend school during one year of that time, but she did finish the seven-year course of study in 1889 and graduated.

She then returned home to her parents in De Smet, South Dakota, and contributed to the family income by making fly nets for horses.

Following her mother's death in April 1924, she lived for a time with her sister, Grace Ingalls Dow in Manchester, South Dakota.

The real Mary Ingalls never became a teacher nor married, but returned to De Smet to live with her parents after graduating from Vinton.