She was the fastest ocean liner in history, widely known as America's flagship, and in her nearly two decades in service, the elegant SS United States carried four presidents, countless celebrities, and tens of thousands of happy voyagers. But the jet age took her out of service, and she eventually wound up docked at a Philadelphia berth for close to 30 years. Now, the SS United States is scheduled to sink off the coast of Florida, to become the world's largest artificial reef. Correspondent Lee Cowan looks back on the history and future of a maritime legend.