9. Pink Floyd
We were initially unsure about counting Pink Floyd as a jam band. Their concerts from 1973 onward were fairly rehearsed, even if songs like "Dogs" and "Shine on You Crazy Diamond" ran for nearly 30 minutes. But during the Ummagumma period things were different, and in the Syd Barrett era they'd play marathon, improvisatory sets around London. They moved far away from this, but jamming remains in their DNA.