[2] The county is named for John Caldwell Calhoun, the seventh vice president of the United States.

Calhoun County comprises the Port Lavaca, TX Micropolitan Statistical Area, which is also included in the Victoria-Port Lavaca, TX Combined Statistical Area.

As of the 2020 United States census, there were 20,106 people, 8,027 households, and 5,502 families residing in the county.

As of the 2010 United States census, there were 21,381 people living in the county.

21.30% of all households were made up of individuals, and 8.90% had someone living alone who was 65 years of age or older.

[29] Our Lady of the Gulf Catholic School, pre-K through grade 8, has also served the county since 1996.