In the show, it is first sung as a duet by the characters Gaylord Ravenal, a handsome riverboat gambler, and the teenage Magnolia Hawks, an aspiring performer and daughter of the show boat captain, soon after their meeting in Act I.
It reveals that they are smitten with each other almost immediately upon meeting and sets the tone for the contrasts between the ideal “make believe” world of the young lovers and the harsh realities of life that they will encounter throughout the story.
In Act II, Ravenal sings it to his little daughter Kim, just before he deserts her and Magnolia because of his compulsive gambling.
The first successful recording[1] of the song was by Paul Whiteman and his Orchestra on January 27, 1928 (vocal by Bing Crosby).
For film, it was sung by Irene Dunne and Allan Jones in the 1936 version of the musical, by Tony Martin and Kathryn Grayson in the 1946 Kern biopic Till the Clouds Roll By, and by Howard Keel and Kathryn Grayson in the 1951 version of Show Boat.