Harmon was born in Newtown, Ohio and named after Adoniram Judson, the famed American Baptist foreign missionary.

[2] Judson was a distant relative of Frances Folsom, the wife of President Grover Cleveland, through her mother Emma Harmon.

Harmon was elected judge of the Common Pleas Court in 1876 but left months later to run unsuccessfully for the State Senate.

[5] In 1910, Harmon was re-elected for a second term as governor, this time defeating future President of the United States Warren G. Harding.

[9] That was largely as a favorite son of the State of Ohio, Harmon found support from elsewhere and on the first ballot of the Convention, and he received the votes of 148 delegates.

[14] Harmon and family were residents of Wyoming, OH and lived at 205 Worthington Avenue, located in the city's Village Historic District.