What exactly does LeRoi Jones mean by "the blues continuum" in his book Blues People: Negro Music in White America?
When LeRoi Jones, or Amiri Baraka, discusses "the blues continuum," he is applying the word "continuum" in dual contexts. The first context involves the history of African Americans and the survival of the ancient cultures that the early slaves brought with them from Africa. What Jones referred to as "the continuing evidence of surviving 'Africanisms' and parallels between African customs and philosophies, mores, etc., and the philosophies and the Afro-American continuum" was the physical and psychological evidence that African Americans, as with white Americans who traced their ancestry to Europe, did not magically materialize or, as he facetiously put it, "did not drop out of the sky." In other words, African Americans and the music they developed represented a historical continuum that stretched back centuries to the forced emigration of Africans from their tribal and ancestral homelands to North America.
The second context in which Jones applied the word "continuum" involved the evolution of the genre of music that provided the basis of his landmark study. Aficionados of jazz rightly connect historical dots from that uniquely American musical genre's origins in the African American experience to its present practitioners. In Blues People, Jones similarly traced the evolution of blues and "rhythm and blues" to the African American experience beginning with slavery and continuing into the "modern" Civil Rights era, circa the early 1960s (Blues People was published in 1963). The blues evolved over many years to include influences from across the African American experience, including the synthesis of the Southern blues tradition with the "musical traditions of the Northern Negro." In other words, "the blues continuum" merely refers to the evolution of that genre of music--an evolution hundreds of years in the making.