Land for sale in Oconee County, South Carolina, recently totaled almost $345 million and 5,000 acres. Oconee County ranks seventh in the Palmetto State for the combined amount of land currently advertised for sale. Seneca had the most land for sale. From an economic perspective, manufacturing and related services are the main sectors in Oconee County. Oconee County is South Carolina's 24th largest county (673 square miles). It's located in the Upstate South Carolina region of South Carolina.