Allendale is a town in Allendale County, South Carolina, United States. The population was 3,482 at the 2010 census, a decline from 4,052 in 2000. It is the county seat of Allendale County.
The Allendale County Courthouse, Antioch Christian Church, Erwin House, Gravel Hill Plantation, Red Bluff Flint Quarries, Roselawn, and Smyrna Baptist Church are listed on the National Register of Historic Places.
The artist Jasper Johns lived in Allendale during his childhood in the 1930s and 1940s. He was raised there by his grandfather, a farmer, and then with his aunt, the only teacher in a two-room school.
In his 2015 book entitled Deep South: Four Seasons on Back Roads, author Paul Theroux describes Allendale as a "ghost town", "poor, neglected, hopeless-looking, a vivid failure."
According to the United States Census Bureau, the town has a total area of 3.3 square miles (8.5 km2), all land.
As of the census of 2000, there were 4,052 people, 1,542 households, and 997 families residing in the town. The population density was 1,225.2 people per square mile (472.7/km2). There were 1,763 housing units at an average density of 533.1 per square mile (205.6/km2). The racial makeup of the town was 18.19% White, 80.03% African American, 0.17% Asian, 0.17% Pacific Islander, 0.96% from other races, and 0.47% from two or more races. Hispanic or Latino of any race were 2.25% of the population.