According to theU.S. Census Bureau, the county has a total area of 447 square miles (1,160 km2), of which 442 square miles (1,140 km2) is land and 4.8 square miles (12 km2) (1.1%) is water.[10] TheSatilla River runs through Brantley County.
The bulk of Brantley County, from east ofHortense south to west ofWaynesville and west to east ofWaycross, is located in theSatilla River sub-basin of theSt. Marys-Satilla basin. The county's eastern border area, east of Waynesville, is located in theCumberland-St. Simons sub-basin of the St. Marys-Satilla River basin. A small northwestern corner, west of Hortense, is located in the Little Satilla sub-basin of the larger St. Marys-Satilla River basin, and a very small southwestern corner of Brantley County is located in the UpperSuwannee River sub-basin of the larger Suwannee River basin.[11]
Brantley County, Georgia – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
As of the2020 census, the county had a population of 18,021. Of the residents, 24.0% were under the age of 18 and 16.6% were 65 years of age or older; the median age was 40.3 years. For every 100 females there were 97.6 males, and for every 100 females age 18 and over there were 95.1 males. 0.7% of residents lived in urban areas and 99.3% lived in rural areas.[24][25][26]
There were 6,915 households and 4,578 families residing in the county; 32.4% of the households had children under the age of 18 living with them and 24.8% had a female householder with no spouse or partner present. About 24.4% of all households were made up of individuals and 10.9% had someone living alone who was 65 years of age or older.[25]
There were 8,143 housing units, of which 15.1% were vacant. Among occupied housing units, 78.9% were owner-occupied and 21.1% were renter-occupied. The homeowner vacancy rate was 1.2% and the rental vacancy rate was 7.9%.[25]
As of the 2020s, Brantley County is aRepublican stronghold, voting 91% forDonald Trump in2024. The lastDemocrat to carry the county wasBill Clinton in 1992, and it has swung hard to the right in the following elections. In 2020,Donald Trump carried the county with 90.2% of the vote, the most out of any county in Georgia.