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When did The Tonight Show Starring Johnny Carson move to Burbank?
On May 1, 1972, the show moved from 30 Rockefeller Plaza to Burbank, California.
Why did The Tonight Show Starring Johnny Carson move to Burbank?
The show moved from 30 Rockefeller Plaza to Burbank, California, because of the studio's proximity to celebrities.
What happened after The Tonight Show Starring Johnny Carson's move to Burbank?
From July 1971, Carson stopped hosting five shows per week. Instead, Mondays featured a guest host, leaving Carson to host the other four weeknights.
What did Johnny Carson do after having a guest host on Mondays for The Tonight Show?
In 1980, at Carson's request, the show cut its 90-minute format to 60 minutes on September 16;
What happened after Johnny Carson requested the shortenting of the The Tonight Show from 90 to 60 minutes?
Joan Rivers became the permanent guest host from September 1983 until 1986.

Question: What else is significant about this move?
Self-contained rewrite: What else is significant about the new format of The Tonight Show with Johnn Carson after introducing rotating and permanent guest hosts?