[3] Named after the French people who originally settled there,[4] its name “Gallia” is the Latin word for Gaul, the ancient region of Western Europe that included present day France.

[5] Gallia County is part of the Point Pleasant, WV-OH Micropolitan Statistical Area.

Gallia County had originally been settled by French immigrants, who named the county "Gallia", the Latin name for Gaul, the ancient region of Western Europe which included present day France.

[6] In the 19th century, the county was settled by numerous migrants from the Upper South, who traveled to the territory by the Ohio River.

In the antebellum years, some of its towns became centers of settlement by African Americans, both free blacks (some also from the South) and refugee slaves who had escaped their owners and come across the river to a free state.

25.20% of all households were made up of individuals, and 10.40% had someone living alone who was 65 years of age or older.

As of the 2010 United States Census, there were 30,934 people, 12,062 households, and 8,264 families living in the county.

Lyndon Johnson in his 1964 landslide is the solitary Democrat to win a majority of the county's vote in the presidential election, although James Buchanan in 1856 and Bill Clinton in 1996 won a plurality.