Conversation so far:
What was Johnny Cash's first show?
Cash began performing concerts at prisons starting in the late 1950s.
How did his early career go?
These performances led to a pair of highly successful live albums.
What were the early albums?
Johnny Cash at Folsom Prison (1968) and Johnny Cash at San Quentin (1969).

Question: Were the albums popular?
Self-contained rewrite: Were Johnny Cash's albums popular?