This was written by Joni Mitchell to commemorate the 1969 festival and three versions were released in 1970.
The first was by Crosby, Stills, Nash & Young and appeared on their March 1970 album Déjà Vu. It was released as a single the same month and reached No 11 in the States.
Mitchell’s own version, from her April 1970 album Ladies of the Canyon, was the B-side to her single Big Yellow Taxi released the same month. Alan, who is the world’s greatest Joni Mitchell fan, can’t bear it.
The third version, by Matthews Southern Comfort, was released in the UK in July 1970 and topped the chart. It was released in the US in November and eventually got to No 83.