By late 1969, Santana could be counted on to attract a crowd, and Bill Graham added less familiar groups to the billing to take advantage of Santana's draw. Grand Funk Railroad was a Michigan transplant, hard-rock band that built up a following with constant touring; Fat Mattress, formed by Jimi Hendrix Experience original member Noel Redding, played progressive rock into the 70's.
During his Fillmore era, from 1969-1971, Singer created more posters for Graham than any other artist. Singer's posters are notable for his use of collage, incorporating thousands of images clipped from magazines spanning several decades. He developed a format that included a stunning variety of lettering styles, applying them in close relation to the theme or subject of a poster.