Plum Branch is a town in McCormick County, South Carolina, United States. The population was 82 at the 2010 census.Plum Branch is located at 33°51′00″N 82°15′34″W / 33.849875°N 82.259560°W / 33.849875; -82.259560.According to the United States Census Bureau, the town has a total area of 0.4 square miles, all land.As of the 2010 Census, the population was 82, 59 were White, 20 were Black or African American, and 3 were two or more races. None were Hispanic or Latino As of the census of 2000, there were 98 people, 43 households, and 26 families residing in the town. The population density was 264.5 people per square mile. There were 52 housing units at an average density of 140.4 per square mile. The racial makeup of the town was 78.57% White and 21.43% African American.There were 43 households out of which 20.9% had children under the age of 18 living with them, 55.8% were married couples living together, 2.3% had a female householder with no husband present, and 39.