The famed Summer Jam at Watkins Glen Music Festival kicked off at the Watkins Glen Grand Prix Raceway in Upstate New York on July 28, 1973. The event featured headlining performances by the Grateful Dead, the Allman Brothers Band and the Band. Over 600,000 fans flooded the rural town for the concert, at the time earning the Guinness world record for the largest audience at a pop music festival. The massive turnout came as a surprise to everyone, including Watkins Glen Grand Prix President Henry Valent.“We never expected the enormous turnout that this festival drew. They started arriving up here Monday, a lot of walk-ins, hitchhikers. We let them right in. Tuesday we put a ticket gate and began the inspection of tickets. As the week wore on the sheer volume of traffic made it impossible to continue our checks,” he told Billboard in 1973.