Some reference material re: Black Origins of Barbershop:

Abbott, Lynn. Play That Barber Shop Chord: A Case for the African American Origin of Barbershop Harmony. American Music 10 (1992) 289-325.
Henry, James Earl. The Origins of Barbershop Harmony: A Study of Barbershop's Links to Other African American Musics as Evidenced through Recordings and Arrangements of Early Black and White Quartets. Ph. D diss., Washington University, 2000


White Barbershop - the men in straw hats and striped shirts arose in the 40s when Barbershop became popular again.

I always assumed that the close harmony rock of the 50s had it's origins in Barbershop as well as Black religious music. Nothing to back it up...