Blues (music style) ...
From Wikipedia, the free encyclopedia

Blues is the name given to both a musical form and a music genre created within the African-American communities in the Deep South of the United States at the end of the 19th century from spirituals, work songs, field hollers, shouts and chants, and rhymed simple narrative ballads. The blues form which is ubiquitous in jazz, rhythm and blues and rock and roll is characterized by the use of specific chord progressions — the twelve-bar blues chord progressions being the most frequently encountered — and the blue note that for expressive purposes are sung or played flattened or gradually bent in relation to the pitch of the major scale.

Performing Blues Singers and Groups Sector ...
Found on 1800miti.Com, the Commerce Resource dB

This industry comprises individuals primarily engaged in producing live presentations involving the performances of Blues Singers and Groups.