Mary Johnson was born 15 November 1908 to John M. Johnson (?-?) and Lulu Rebecca Doty (1874-1950) and died 28 December 1983 of unspecified causes. Ancestors are from the United States, Ireland, Switzerland.
Mary Claire Johnson was never married. She lived in her cousin Esther May Nesbitt's house in Sycamore, Illinois, and commuted by train to her job with the State of Illinois in Chicago.