This song was written by group leader John Fogerty, who explained: "Green River is really about this place where I used to go as a kid on Putah Creek, near Winters, California. I went there with my family every year until I was ten. Lot of happy memories there. I learned how to swim there. There was a rope hanging from the tree. Certainly dragonflies, bullfrogs. There was a little cabin we would stay in owned by a descendant of Buffalo Bill Cody. That's the reference in the song to Cody Jr. ["Up at Cody's camp I spent my days..."]
The actual specific reference, Green River, I got from a soda pop-syrup label. You used to be able to go into a soda fountain, and they had these bottles of flavored syrup. My flavor was called Green River. It was green, lime flavored, and they would empty some out over some ice and pour some of that soda water on it, and you had yourself a Green River."