Beware of Mental-Itis! Industrial. The Calvin Company, 1937. http://archive.org/details/0800_Beware_of_Mental-itis_06_00_55_00.

Medicine shows became popular after the Civil War when patent medicine salesmen traveled the "kerosene circuit" in rural America. Flourishing until the passage of 1906 Fair Food and Drug Act made them obsolete, medicine shows provided entertainment to attract audiences and then used their intermissions to sell their products.

This pattern would later be seen in later radio and television when product pitchmen sponsored entertainment in return for commercial time.

(Bob Dylan, Theme Time Radio Hour, "Doctors," February 20, 2008 via http://www.oldhatrecords.com/)

See also: https://en.wikipedia.org/wiki/Medicine_show

Also related to tent revival shows which featured music and religion as entertainment and socializing.

Example in music: Neil Diamond's song: Brother Love's Travelling Salvation Show