Barnwell, county, southern South Carolina, U.S. It consists of a low-lying region on the Coastal Plain bordered to the northeast by the South Fork Edisto River and to the southwest by the Savannah River border with Georgia. The county is also drained by the Salkehatchie River. Wetlands and pine woods dominate the region. The largest portion of the U.S. Department of Energy’s Savannah River Site, once a major producer of nuclear weapons materials and now operating in a much-diminished capacity, is in western Barnwell county. Barnwell State Park lies within the county’s borders.

In 2019, Barnwell County, SC had a population of 21.3k people with a median age of 41.3 and a median household income of $35,803. Between 2018 and 2019 the population of Barnwell County, SC declined from 21,577 to 21,346, a −1.07% decrease and its median household income declined from $36,566 to $35,803, a −2.09% decrease.

99% of the residents in Barnwell County, SC are U.S. citizens.

In 2019, the median property value in Barnwell County, SC was $81,900, and the homeownership rate was 69.6%. Most people in Barnwell County, SC drove alone to work, and the average commute time was 30.9 minutes. The average car ownership in Barnwell County, SC was 2 cars per household.

Barnwell County, SC borders Burke County, GA, Aiken County, SC, Allendale County, SC, Bamberg County, SC, and Orangeburg County, SC.