Phil Garris, who did the art for the Blues for Allah cover, used some visual puns in this tombstone with a skull for the Grateful Dead and an owl for the Whooo. This poster was printed twice by Bill Graham and also bootlegged extensively. Original posters like this one are quite scarce, despite 5,000 pieces being printed.
By the early 70s, fans, cities and promoters were tired of huge events in a muddy field (Woodstock, Altamont, etc…), and Bill Graham was in the vanguard of staging rock concerts in football stadiums. The stadium shows were usually all-day affairs with several bands, giving everyone a taste of a rock festival, but with adequate parking, food and facilities. Bill Graham's Day on the Green concerts were the first prototypes of "festival" shows – multi-performer sets in stadium settings.