Wilhelm was born in Haworth, New Jersey, USA, on 14 May 1906, the first child of Norman Ley Harris and Angelica Caroe. Her mother was born in Denmark. She had four siblings: Helen Huntington, Alma Ruth Harris, Norma Lee O’Hara and Norman Ley Harris. In 1914, the family moved to San Angelo, Texas, where her father, an optometrist, owned and operated an optometry shop until his passing in 1922. Around the same time, her younger sister Alma also passed away at a young age. The family would soon move to Bronx, New York, where her mother’s relatives lived. Her mother lived to be 104.

Before getting married, she worked for a publishing company in New York City. In August 1933, she married Francis A. Wilhelm, whom she had met through her sister Helen’s boyfriend. The couple had no children. The couple resided in various cities and naval bases across the U.S. before settling in Huntsville, Alabama, in 1963. Her husband passed away of cancer within months of his retirement in 1972. She traveled to numerous locations worldwide, including Hawaii, Panama, Tokyo, Greece, Egypt, and the South Pacific, often accompanied by her sisters Helen and Norma Lee.

In 2012, at the age of 105, she traveled to Florida to visit her relatives. During the flight, the flight attendant announced her as the oldest passenger on board, prompting applause from everyone. She was a member and benefactor of St. Thomas Episcopal Church.

Wilhelm passed away in Huntsville, Alabama, USA, on 31 July 2016, at the age of 110 years, 78 days.