(dick greenhaus here)

In case nobody's noticed, there's been a dearth of black folk performers (and blacks in folk audiences) since the separatist movement of the mid-to-late 1960s. THis is most evident in the development of the blues genre as something distinct from the folk genre. Calypso and gospel too, have gone their separate ways---I suspect that, back in the 50s both would have fallen under the "folk" blanket. Maybe reggae, too.