Between the World Wars, electronic communication forms came into their own. And with it came country religious music: the type that evolved far away from the grand cathedrals of the cities, played and sung by community members in small rooms they built to be churches, or barns. In some places, this is still the way things are.
With radio, came radio stars. The birth of Country Music, Jazz, and Rock'n'Roll all come from the days of the traveling minstrel shows, accompanying preachers of all sorts.
Shaped notes were devised to help the crowd find their voice--to note emphasis and expression with something other than ancient Italian or Latin words which had not meaning or history to the people singing.
Renfro Valley (KY) remains a media center for this type of music, with museums, classes and performance venues.
The Cash quartet from Rockcastle County, Kentucky, formed around 1956 as
the result of singing together at the Ottawa Baptist Church. Members
included Walter Cash, wife Reba, Walter's sister Joanne, and R.H. Hamm.
Like many other amateur gospel groups at the time, they were not
interested in commercial recording. They sung only occasionally on the
nationally heard Renfro Valley Gatherin'. However they gained a local radio following through their own weekly program, Sinclair Sunday Serenade,
over Renfro Valley's WRVK. They were busy as well with frequent
appearances at local and regional gospel singing events, something they
continued after they stopped radio performing in the late-1960s.
While there are no recordings available commercially, they can be heard via the Berea Sound archives on scratchy old reel-to-reel tapes digitally transcribed.
While there may be some familial connection between this family and Johnny Cash the connection is most probably distant. The Appalachians are full of families that arrived before the Revolution and grew and spread throughout the region. We did not look.