Mary Jane “Minnie” Sullivan was born on January 14, 1866 in Flint, Genesee, Michigan to Thomas O’Sullivan and Johanna “Hannah” (FitzGerrold) O’Sullivan. She spent her childhood in Flint, moving to Dexter, Washtenaw, Michigan sometime during her adolescence. On February 11, 1884 she was married to John Charles Daly in Aberdeen, Brown County, South Dakota. They had five children: Walter Edward (b. 1885), Charles “Charlie” Carl (b. 1886), Florence E (b. 1888), Marion Agnew (b. 1890), and Dorothy (b. 1894).
The family resided in Columbia and Aberdeen (Brown County), South Dakota from the 1880s onward. Minnie died on February 27, 1923 in Aberdeen.