Photo #29056 - City of Seneca. Seneca is located in Oconee County, which forms the northwestern tip of South Carolina and borders both Georgia and North Carolina. Seneca is an Iroquois Indian word, and 'Seneca City' was founded in 1873 Bounded at one end by the port city of Charleston and at the other by the Blue Ridge Mountains, the South Carolina Heritage Corridor contains historic, cultural, and natural resources that tell the lively story of South Carolina's centuries long evolution and culture. Learn of rice and indigo, pirates and patriots, slaves and freemen, cotton fields and mill villages, swamps and waterfalls, railroads and back roads, spirituals and bluegrass.