You might think of the Mississippi River as the central artery of North America. More than 300 species of birds - billions of birds - make their way north from Central and South America every year along the Mississippi Flyway, with the river at the heart of their route. The young Samuel Langhorne Clemens - later known as Mark Twain - loved the sounds of the river. He signed on to train as a pilot on a riverboat when he was just 22. And Twain quickly discovered that if he volunteered for the early morning shift, he could experience one of the most incredible musical shows there is.