Greene County is located in the southwestern portion of Ohio.

[2] Its county seat is Xenia and its largest city is Beavercreek.

[3] The county was established on March 24, 1803[4] and named for General Nathanael Greene,[5] an officer in the Revolutionary War.

Greene County is part of the Dayton, OH Metropolitan Statistical Area.

[6] As of the census[12] of 2020, there were 167,996 people, 65,915 households, and 42,983 families living in the county.

27.7% of all households were made up of individuals, and 3.0% had someone living alone who was 65 years of age or older.

[19] As of the 2010 United States census, there were 161,573 people, 62,770 households, and 41,696 families living in the county.

[23] As of the census of 2010, there were 161,573 people, 61,825 households, and 39,160 families living in the county.

23.00% of all households were made up of individuals, and 7.70% had someone living alone who was 65 years of age or older.

Greene County is a Republican stronghold in presidential elections.