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.