An island in the Ohio river, once home to Harman and Margaret Blennerhassett, and still a popular tourist attraction in the Marietta, OH and Parkersburg, WV area.

Margaret, Harman's wife, was also his niece. Thus, legend has it that their flight to the island was in part because of this incestuous relationship.

Aaron Burr met with Harman Blennerhassett (an exiled Irish aristocrat) on the island, along with James Wilkinson (a General of the US Army). This was the beginning of the Burr conspiracy.

Janice Hofmann wrote a book (historical fiction), Tragedy & Treason that takes place on Blennerhassett Island.