Conversation so far:
When was the museum created?
When the National Baseball Museum opened on June 12, 1939 in Cooperstown New York.
What was notable about the museum?
it remained to be determined how the membership in its Hall of Fame would be determined in the future.
Was anything eventually decided about the membership?
The Baseball Writers' Association of America (BBWAA) had determined to vote every three years rather than annually.

Question: Who was associated or involved in the museum?
Self-contained rewrite: Who was associated or involved in the National Baseball Museum?