[3] The county is named after John Adams, the second President of the United States.

[6] As of the 2000 United States census,[13] 27,330 people, 10,501 households, and 7,613 families resided in the county.

24.00% of all households were made up of individuals, and 11.00% had someone living alone who was 65 years of age or older.

As of the 2010 United States census, 28,550 people, 11,147 households, and 7,793 families resided in the county.

[17] As of the 2020 United States census, 27,477 people, 10,175 households, and 7,483 families resided in the county.

[19] A 2019 report identified Adams County as the poorest in Ohio with a 23.8% poverty rate and median household income of $36,320 ($16,000 less than the state average).

Poor economic conditions led to a 2.1% decrease in the county's population during the previous five years.

Adams County's elected commissioners are: Ty Pell, Diane Ward, and Barbara Moore.

[22] The Adams County Public Library serves the communities of Adams County, Ohio from its administrative location in Peebles and branches in Manchester, West Union, and Seaman.

It was renamed and relocated to Seaman, and is easily accessible from the Appalachian Highway.