structures. A testimony of those times can be found for instance in Henry Thomas's recordings. However, the twelve-, eight-bar, or sixteen-bar structure based on tonic, subdominant and dominant chords became the most common. Melodically, blues music is marked by the use of the lowered third and dominant seventh (so-called blue notes) of the associated major scale. The standard 12-bar blues form is noted in uncorroborated oral histories as appearing communities throughout the region along the lower Mississippi River during the decade of the 1900s (and performed in New Orleans at least since 1908). One of these early sites of blues evolution was along Beale Street in Memphis, Tennessee. However, author Eileen Southern has pointed out several contrasting statements by old-time musicians. She cites Eubie Blake as saying "Blues in Baltimore? Why, Baltimore is the blues!" and Bunk Johnson as claiming that the blues was around in his childhood, in the 1880s. Growth of the blues (1920s onward) One of the first professional blues singers was Gertrude "Ma" Rainey, who claimed to have coined the term blues. Classic female urban or vaudeville blues singers were popular in the 1920s, among them Mamie Smith, Ma Rainey, Bessie Smith, and Victoria Spivey. Mamie Smith, more a vaudeville performer than a blues artist, was the first African-American to record a blues in 1920; her "Crazy Blues" sold over 75,000 copies in its first month. The musical forms and styles that are now considered the "blues" as well as modern "country music" arose in the same regions during the nineteenth century in the southern United States. Recorded blues and country can be found from as far back as the 1920s, when the popular record industry developed and created marketing categories called "race music" and "hillbilly music" to sell music by blacks for blacks and by whites for whites respectively. At the time, there was no clear musical division between "blues" and "country", except for the race of the performer, and even that sometimes was documented incorrectly by record companies. Notes References Blues Blues