What an informative posting, Miles! Thank you.

It's hard to believe that AL didn't know what the "Mississippi Delta" was. Without putting too fine a point on it, some of the texts and even some documentation in his Folk Songs of North America (1965) suggest to me that he wasn't as wed to absolute accuracy as academic standards would now require.

Because the Mississippi is the major waterway of the South, it certainly makes sense that river traffic played a significant role in spreading the blues, especially if its origin was in a city like Memphis or Vicksburg (or even St. Louis).

Influenced by unreliable or (necessarily) partially informed sources sources (who provided the only evidence he had), and by his personal experiences in the Delta, AL might easily have jumped to the conclusion that the Delta was the birthplace - especially since blues were very widely played there. And the phrase "the Delta" is so much punchier and more colorful than "somewhere in the lower Mississippi Valley."

That overconfidence would also give him the satisfaction of making a significant ethnomusicological discovery.

And let's face it, probably no one knew more about "blues history" in the 1950s than AL.

It may be impossible to determine with any precision just where or when the blues originated, because the evidence is necessarily scanty. To say, for example that the blues was known in Arkansas before 1910 and maybe existed by 1895, isn't saying much.

Nor is the issue isn't helped by the fact that, except for spirituals and the occasional banjo/fiddle tune, African-American musical culture was of little interest to the wider world in the nineteenth century.

Absence of evidence here is not evidence of absence - because before Lomax, virtually nobody was looking for the evidence.

And once "born" or "invented," how long the blues might have taken to spread and become a "genre" is likely unknowable. There are simply no records.