This chapter traces the complex results of a paradigm shift: around the middle of the twentieth century, commercially mediated working-class and rural musics disrupted the dominance of Tin Pan Alley popular song. Records became more important than sheet music, and oral traditions grew ever more audible and less local. The music industry resisted these changes, which rewarded ‘untrained’ performers and songwriters, upstart record companies, and eccentric disc jockeys more than the composers, arrangers, copyists, crooners, and studio orchestras of the reigning commercial system. But by 1952 the value of record sales exceeded that of sheet music, and the handful of major record companies saw their share of the popular music market drop from 78 percent in 1955 to 34 percent in 1959, even while that market tripled in size during those few years. Never before had the sentiments and critiques of working-class music been so accessible and persuasive to other groups. Previously separate audiences found new affinities as mass culture offered them fresh pleasures and identities. Music that had expressed the world views of primarily marginal groups brought its styles and sensibilities to the center stage of American life.

From the early days of the recording business, genre categories served to separate artists and audiences along racial lines, implying that “race records” and “hillbilly, ” for example, came from mutually exclusive sources. But demographic shifts encouraged cultural mixtures throughout the twentieth century: not only generational changes, but perhaps more importantly, the mass movements of people from the country to the cities.