But by the time Mitchell, Crosby, Stills and Nash arrived at JFK airport, everyone knew about the logistical challenges at Woodstock. Mitchell’s agent, David Geffen, was concerned that she may not make it out of the festival site in time to appear on the Dick Cavett Show.
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And so it was that Joni Mitchell, the writer of the song inspired by the most iconic music festival of all time, wasn’t actually at the event.
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Joni Mitchell and Graham Nash were romantically involved at the time, and it would be Nash’s observations of the festival that would help inform Mitchell’s lyrics for the song.

https://jonimitchell.com/library/view.cfm?id=5978