July 20, 1967 is the hero: a Thursday and the opening night of FD-72, "Family Portrait," a Dennis Nolan poster, for a run of July 20-23 at the Avalon Ballroom. The bill split across the run in a way worth laying out. Big Brother and the Holding Company - with Janis Joplin - shared the top with Mount Rushmore on July 20-21, then Canned Heat and Mother Earth took over for July 22-23, with Mount Rushmore holding across all four nights as the connective thread. That's the opening night here: Joplin's Big Brother and Mount Rushmore under Nolan's "Family Portrait."

A year later, July 20, 1968 produced two competing core artifacts on the same Saturday night, and both deserve to be logged openly. At Fillmore West, it was Sly and the Family Stone, the Jeff Beck Group, and Siegel-Schwall - the July 19-21 leg of Lee Conklin's BG-129. Conklin's authorship of that poster is confirmed, which is worth stating flatly because an earlier attribution to David Byrd has been refuted; the credit is Conklin's. Across town at the Avalon, meanwhile, it was night two of FD-128 - Tim Buckley, the Velvet Underground, and Allmen Joy. Two core posters, two core rooms, one Saturday.

July 20, 1969 carries the single largest piece of outside history to intersect the window, because that Sunday was the night of the Apollo 11 moon landing. The ballrooms were open: Fillmore West ran its BG-182 leg - Country Joe and the Fish, Joe Cocker, Country Weather - and the Family Dog on the Great Highway was also open with its July 18-20 bill of Sir Douglas Quintet, Kwan Dios, and Bicycle. The Grateful Dead, notably, had no show that night; per lostlivedead, they gathered at Garcia's house to watch the landing instead. One correction belongs here to keep the record clean: this is not the night to place Ike and Tina Turner - that's a misdated June 1969 bill belonging to BG-178, not to this Sunday.

July 20, 1965 and July 20, 1966 are both nulls, a Tuesday and a Wednesday with nothing at the core venues.