Kohl was born as Rachel Gertrude Branstetter in Curryville, Pike County, Missouri, United States, on 28 June 1909. Her parents were Enoch Hall Branstetter (1876–1963) and Ruby Rachel Bratcher (1883–1979). She had six siblings (five sisters and one brother).
After graduating in 1927 from Vandalia High School, she started on a career track in education that would last, aside from a short time in secretarial work, most of her working life. She started teaching in country schools, riding a horse to work each day. She was involved in rural education until 1958 when the country and town schools were consolidated. After that, she was employed in the Van-Far School system as a teacher and librarian for 21 years until her retirement in 1977.
In October 1935, she married Richard Henry Kohl. He died in February 1991, after 55 years of marriage. In September 2017, she celebrated 90 years since graduation from the Van-Far/Vandalia High School.
Kohl died in Laddonia, Missouri, USA on 17 November 2022, at the age of 113 years, 142 days. She was survived by four children, six grandchildren, 11 great-grandchildren and 8 great-great grandchildren.
At the time of death, she was the oldest known person living in the U.S. state of Missouri.
Her age was verified by Stefan Maglov, and validated by LongeviQuest on 10 February 2023.