Among the formal, identifying musical traits of the blues are the familiar “blue notes,” a three-line AAB verse form, and a characteristic use of the familiar blues chord progression. Historically, the popularity of blues coincides with the rise of the commercial recording industry, the introduction of “race” records aimed at black record-buyers after 1920, and the emigration of black Americans from the rural South to the urban North. Many of the earliest black American recording stars were blues singers. The first blues songs to be recorded, often called “classic blues,” were jazz-influenced songs in a vaudeville style, sung by the great blueswomen: Gertrude “Ma” Rainey, Bessie Smith, and others. These singers were often accompanied by pianists,
