I think I solved a mystery that may not have existed: the website Spencer found that I yoinked these pics from says they’re from 6/22/68 at the Star Theater in Phoenix, but the rest of the innertubes say that the Dead played the Star in 1970.
Our date is correct (as evidenced by everyone’s clothes and guitars), but the venue is wrong: this was the Travelodge Theater in Phoenix, not the Star.
Everyone can relax now.
(If you’re wondering why I’m not linking to the show, it’s because the photos are all that remain. The saddest four words in Enthusiasm: no recording was made.)