South Dakota Facts

Mount Rushmore has a secret: a 70-foot granite tunnel cut directly behind the faces. Sculptor Gutzon Borglum began drilling it in 1938 to house America's founding documents for future civilizations. Congress shut the project down in 1939 and Borglum died in 1941. In 1998, his family lowered 16 porcelain panels into a titanium vault and sealed it under a 1,200-pound granite capstone. Nobody can go inside.