Reaver was born in a one-room cabin near Silver Run, Carroll County, Maryland, USA, on 7 December 1878, to parents John F. Carl (1854–1910) and Margaret A. Slonaker (1857–1945). She attended the Erb School on Stone Road near Mayberry for several years before assuming a position as general hand on a farm off Babylon Road. She was making about a dollar a week there.

At the age of 23, she married Elmer C. Reaver (1875–1964). The couple established their home on a farm outside Littlestown, Pennsylvania. They lived on a number of farms in Carroll County and in Pennsylvania. They had a son, who died in infancy in July 1902. Her husband also worked at Woods’ machine shop in Chambersburg, Pennsylvania, where the couple lived from the 1920s through the 1950s.

Her husband passed away in 1964, aged 88. At the age of 100, she was living at her Westminster apartment, still doing all housework. She mentioned that she drank a lot of hot water, rarely tea and never coffee. Her diet primarily consisted of home-grown food, and she made an effort to stay active as much as possible. She continued living independently until she was 106, when she moved to the Westminster Nursing and Convalescent Center.

Reaver passed away after a brief illness in Westminster, Maryland, USA, on 2 March 1989, at the age of 110 years, 85 days.