"Old Man River" is not only the most famous song from the 1927 musical Showboat but one of the most loved songs in Broadway history. Showboat was a unique musical at the time because it was the first serious production in which the plot of the story was as important as the songs. Based on Edna Ferber's novel by the same name, it involves romantic tragedy and racial prejudice. The story spans 40 years, from 1887 to 1927. It is about the entertainment boat, Cotton Blossum, the owner of the boat and his family, the entertainers on the boat, and the dock workers connected with the boat. "Old Man River" is sung by an African-American dockworker who compares the struggles of those people facing poverty, racism and unrelenting toil with the ongoing flow of the Mississippi River. The song is unusual for a musical as it is sung by a deep base voice in a slow tempo. Paul Robson was one of the earliest singers to make this song famous. Later in the 20th century, William Warfield sang the song in revivals of the musical.