Question: what was the grateful dead's biggest hit

title: Grateful Dead
text: With the exception of 1975 , when the band was on hiatus and played only four concerts together , the Grateful Dead performed many concerts every year , from their formation in April 1965 , until July 9 , 1995 . Initially all their shows were in California , principally in the San Francisco Bay Area and in or near Los Angeles . They also performed , in 1965 and 1966 , with Ken Kesey and the Merry Pranksters , as the house band for the Acid Tests . They toured nationally starting in June 1967 ( their first foray to New York ) , with a few detours to Canada , Europe and three nights at the Great Pyramid of Giza in Egypt in 1978 . They appeared at the Monterey Pop Festival in 1967 , the Woodstock Festival in 1969 and the Festival Express train tour across Canada in 1970 . They were scheduled to appear as the final act at the infamous Altamont Free Concert on December 6 , 1969 after the Rolling Stones but withdrew after security concerns . `` That 's the way things went at Altamont -- so badly that the Grateful Dead , prime organizers and movers of the festival , did n't even get to play , '' staff at Rolling Stone magazine wrote in a detailed narrative on the event ''