Modoc is a census-designated place in McCormick County, South Carolina, United States. The population was 256 at the 2000 census, and 218 at the 2010 census, a decline of 14.8%.The Modoc CDP was named for the Modoc indigenous tribe of Northern California, some members of which had been captured after the Modoc War. They were sent, first to the Indian Territory and then, a few, on to an area on the left bank of the Savannah River in what was then Edgefield County, South Carolina. The 1930 Census of the township of Modoc, by then in McCormick County, had no listings of any "Indians".Modoc is located at 33°42′53″N 82°13′6″W / 33.71472°N 82.21833°W / 33.71472; -82.21833.According to the United States Census Bureau, the CDP has a total area of 7.2 square miles, of which 4.1 square miles is land and 3.1 square miles is water. Its elevation is 401 to 413 feet above sea level.As of the census of 2000, there were 256 people, 120 households, and 78 families residing in the CDP.