August 6, 1966 was a Saturday, and it was the second and final night of a Fillmore Auditorium weekend that Bill Graham had built around Love — Arthur Lee's band down from Los Angeles, the first rock group signed to Elektra, and one of the very few SoCal acts the San Francisco scene took seriously that summer. Wes Wilson drew the poster, BG-21, and every reachable catalog record (rockposters.com, the Burnside and D. King galleries) dates it as a two-night run, Friday and Saturday, August 5 and 6, 1966 — not the three-night Aug 5–7 weekend a first research pass had assumed. The support act both nights was the Everpresent Fullness, another Los Angeles band, which makes this a rare all-Southern-California bill on Graham's stage.

It is worth pausing on what BG-21 looks like in the sequence of Wilson's work. In August 1966 he was a few months from the fully melted, flame-lettered style that would define the Fillmore look by the end of the year; BG-21 is still transitional, the lettering legible, the psychedelic vocabulary arriving but not yet total. The poster is a small marker of how fast the visual grammar of the scene was changing — the same designer, the same venue, would be nearly unrecognizable by November.

Love's own history complicates any tidy "SF vs LA" story. Lee's band never toured much — famously so — and a San Francisco booking at the Fillmore was not a routine stop for them the way it was for the local Avalon-and-Fillmore regulars. The band that would record "Forever Changes" a year later was, in August 1966, touring behind its first album and the single "7 and 7 Is," and the Fillmore date sits in that early window, before the myth hardened. We hedge the finer details of the set — no reliable setlist survives for these two nights from a vetted source — but the bill, the venue, the designer, and the two-night frame are corroborated across chickenonaunicycle's Fillmore Auditorium list and multiple poster-catalog records.

The rest of August 6, 1966 in San Francisco was busy in a way that shows how thick the calendar had already become. Across town at the Avalon, the Family Dog was running the second half of a Bo Diddley engagement — Bo Diddley and Sons of Adam, the Saturday leg of the "Dollar Bill" poster FD-19 (Mouse and Kelley), which our chronicle already carries as the August 5 hero; that engagement's Aug 6 night sits just outside a clean day-page of its own. A year and two years on, the same date would host closing nights of major runs — the Muddy Waters / Buffalo Springfield / Richie Havens run at the Fillmore (BG-76, Bonnie MacLean) closed on Sunday, August 6, 1967, and the Charles Lloyd Quartet's Avalon run (FD-74, Bob Fried) closed the same night — and, in 1968 and 1969, the opening legs of two of the more interesting split-week Fillmore West posters, BG-132 and BG-185, both of which the chronicle treats on their own days later in this week.

But the hero of August 6 is Love at the Fillmore: a Los Angeles band on a Wes Wilson poster in the transitional summer of 1966, a reminder that "the San Francisco sound" was, from the start, porous at its southern edge.