Original 1st printing 14&1/2 x 22&1/2" concert poster for "Happening '67", sponsored by radio station KDWB and featuring Jefferson Airplane appearing along with Buffalo Springfield (with Stephen Stills and Neil Young), the Shadows of Knight and the Electric Prunes at the Minneapolis (MN) Convention Hall from 7/19-21/1967. Design by Joaquin (featuring the 1967 "Surrealistic Pillow" promo photo by Herb Greene), medium-thick flat index stock poster is in near mint to excellent (A-/B+ to B+) condition; aside from a small amount of surface smudging in the left center margin, a tiny edge ding or two, a touch of handling and a slight curl to the paper, it is an absolutely STUNNING example of this ultra-psychedelic regional poster featuring an all-star fuzz-rock/psych-folk lineup and a KILLER design.