ABSTRACT
This chapter discusses 12-bar blues, harmonic substitution, blue notes, and blue note scales. Few things musical are as uniquely American or as timeless as the blues. Born and nurtured in the nineteenth-century rural South, the blues migrated North and into the cities in the early twentieth century, undergoing a process of maturation and refinement that continues to the present day. The blues pattern tolerates endless tinkering, most of it involving tri-tone substitution and/or the addition of tonicizing chord groups. The minor-key blues appears to have a history as old as the major-key form. The principal difference lies in the tonic and subdominant harmonies, which are minor rather than major. Blues melodies are heavily laced with blue notes—pitches, most notably the third and seventh scale degrees, slightly flatter than their equal-tempered counterparts. The origin of blue notes is wrapped in the faded years of the nineteenth-century rural South, but theories exist.
