For decades, the Delta Queen's tall stack has been a familiar sight in St. Paul and other river towns such as Red Wing and Winona. Children wave and a vintage steam calliope plays as the elegant 81-year-old steamboat majestically makes her way down the Mississippi, bound for ports including St. Louis or Hannibal, Mo. The Queen is the last steam-powered riverboat still carrying overnight passengers on American waters. With her Tiffany lamps and rare Siamese ironwood floors, she recreates a bygone era -- down to a bell from the steamboat that carried Mark Twain as he researched his "Life on...