Chesney was born as Mary Clark Manion in Randolph County, Missouri, USA, on 3 August 1912, to parents James William Manion (1880–1974) and Gertrude Finnell (1877–1974). She had two older siblings: Finnell Biggerstaff Manion (1907–1987) and Elizabeth Greene (1910–2000). The family lived on a farm in Clifton Hill.
On 15 March 1933, she married Wallace Chesney. The couple had no children. They were married for 63 years, until her husband’s passing in April 1996.
Over the years, Chesney has loved to play cards and sew. She drove until she was 102, and lived on her own until she was 104.
Chesney currently lives in Moberly, Missouri, USA.
Following the death of 112-year-old Velma Hinds on 8 June 2023, Chesney became the oldest known living person in Missouri.
Her age was validated by LongeviQuest on 22 June 2023.
* “James William Manion” – FindAGrave
* “Mary Chesney celebrates her 109th birthday” – Moberly Monitor-Index, 4 August 2021
* “EmVP: Moberly woman celebrates her 110th birthday” – KOMU-TV, 3 August 2022