Theatrical production that is characteristically sentimental and amusing in nature, having a simple but distinctive plot and offering music, dancing, and dialogue. Its roots can be traced to 18th- and 19th-century genres such as ballad opera, singspiel, and opéra comique. The Black Crook (1866), often called the first musical comedy, attracted patrons of opera and serious drama as well as those of burlesque shows. European composers such as Sigmund Romberg brought to the U.S. a form of operetta that was the generic source for musical comedy. George M. Cohan ushered in the genre's heyday, and in the 1920s and '30s it entered its richest period with the works of Jerome Kern, George Gershwin and Ira Gershwin, Cole Porter, Richard Rodgers, and Oscar Hammerstein. Kern and Hammerstein's Show Boat (1927) was perhaps the first musical to employ music thoroughly integrated with the narrative. The genre flourished in the 1950s with works by composers such as Leonard Bernstein, but it began to decline in the late 1960s, by which time musicals had begun to diverge in many different directions, incorporating elements such as rock music, operatic styling, extravagant lighting and staging, social comment, nostalgia, and pure spectacle. Later notable musical composers included Stephen Sondheim and Andrew Lloyd Webber.