more about the era of popular song and the musical Stage

Early in the 20th century, before radio, phonograph, or television, popular songs were written in places like Tin Pan Alley mainly to promote the sale of sheet music to the public and to professional vaudevillians. Mostly, people played sheet music in their homes the piano. Then the musical revue came along, which incorporated these kinds of popular songs as well as others written especially for performance. The staging existed principally as a vehicle to support the music. Gradually there evolved the kind of musical stage we knew in the mid-20th century called the Broadway musical, where professional song writers developed music especially for performance on stage that was integrated with the plot and served to develop character and advance the story.

Throughout this evolution, popular music and stage music became much the same thing. Many songs—especially romantic ones—written for the stage became hits off stage, and vice versa. Song writers who wrote for the stage heard their music played on radio or records; they heard it sung in the movies and saw it sold in sheet music stores. Sometimes the performer who popularized a piece on stage would also record it or sing it live on radio or in a night club, supper club, or hotel ballroom, a practice which continues today.

Many successful popular song writers wrote nothing for the stage, but their work influenced those who wrote for the stage, and vice versa. What it took to make a ballad appeal to the public at large was much the same as what it took to make it appeal to the theater-going public. "Moon in June" style ballads written for the stage were made of the same stuff as ballads not written for the stage; they sounded alike and conveyed the same kinds of inspiration. These kinds of standards came from both sources.

The career arc of many professional popular song writers paralleled the evolution of the musical theater and the popular song. Many song writers who got their start auditioning sheet music in Tin Pan Alley late in the 19th century and in the first decade of the 20th century became successful writers for the musical revue, then for the musical stage and for movies, and finally for the Broadway musical. Many who wrote hits for the public at large also wrote specifically for the musical theater. Names like George and Ira Gershwin, Cole Porter, Rogers and Hart, and Irving Berlin, became synonymous with musical comedy, even though their roots lay elsewhere. Many of their songs, written specifically for the stage or the movies, became popular successes on radio and records; many of their songs not written specifically for the stage were incorporated in movies and became ballads.

Possibly, Rogers and Hart were the exception that proves the rule. A music industry pundit once advised them that they would have to write ballads if they were to reach a larger market, sell more songs, and make more money, pointing out that the market for stage music was comparatively limited. Heeding the pundit's advice, thereupon they wrote Blue Moon, a smash hit. Blue Moon was first hit they wrote that wasn't written for the stage, and the last. It seems that they could write a successful ballad if they wanted to; they just didn't want to.

The gap between popular music and stage music widened after Hart's association with Rogers ended. Prior to Hart's death in 1948, Rogers took a new partner, Oscar Hammerstein II. Starting with Rogers and Hammerstein and Oklahoma in 1943, and seconded by Lerner and Lowe, the musical revue, which through the 1920s, 30s, and 40s was little more than a collection of loosely-connected or even unconnected song sequences performed on stage, became the musical theater.

As mentioned above, in the musical theater song plays a central role in advancing plot and in characterization. A song whose main purpose is to advance plot and characterization has less chance of appealing to a general audience than a ballad. As theatrical songs became progressively more specialized, more functional, serving the theatrical needs of the drama, they tended to have less universal appeal than their predecessors; they lacked the same popularity. The era when popular song and the musical stage overlapped gradually drew to a close.

Today, stage music as a genre is more distant and distinct than ever from popular music. The work of Frank Lloyd Weber, who wrote Cats, from which we get Memories, is a notable example; so, also, is the work of Stephen Sondheim, who wrote A Little Night Music, from which we get Send in the Clowns. Although these songs, written for stage performance, are well known, arguably they are not classifiable as "popular." Certainly, they are not ballads in the traditional sense. They illustrate the maxim that a well-known song is not necessarily the same thing as a popular song.