In 2021, the event was only 9 days instead of 11, and it occurred in September rather than during the summer months. Stages and other venues The Summerfest grounds include seven permanent stages and two pavilions that can be converted to stages (Johnson Controls World Sound Stage and the South Pavilion). Concert history year by year Summerfest has been most famous for its music since the first festival in 1968, when acts such as Ronnie Dove, The New Colony Six, The Robbs and Up With People performed. Since then, musical acts from Bob Dylan, The Jackson 5, Frank Sinatra, Prince, Whitney Houston, The Jonas Brothers, Fleetwood Mac, Maroon 5, Fun, Britney Spears, Stevie Ray Vaughan, Cher, Tina Turner, and James Taylor to Christina Aguilera, Diana Ross, Roy Orbison, Liza Minnelli, Kanye West, Kid Cudi, Stevie Wonder, Mary J. Blige, Wiz Khalifa, Imagine Dragons, Nine Inch Nails, The Ramones, Billie Eilish, Willie Nelson, The Rolling Stones, and Paul McCartney have graced the Summerfest stages. Acts with Milwaukee and Wisconsin connections have had a prominent history at Summerfest, most notably the BoDeans, The Gufs, Danny Gokey, and Violent Femmes. The concerts have been mostly civil events, with two notable exceptions. In 1970, a performance by the late-arriving Sly & the Family Stone nearly resulted in a riot. In 1973, a performance by Humble Pie & Jo Jo Gunne resulted in a riot, a bonfire, and about 300 arrests. As a result of the latter concert, organizers shied away from rock bands for several years, and established guidelines for "family-friendly" acts and a ban on alcohol brought in by patrons. This was properly managed when Henry Jordan found the experienced managers: Joel Gast and Lou Volpano, to manage entertainment in-house, eliminating Cleveland's Jules Belkin Promotions, who were hired by Board Members Bernie Samson and Steve Marcus. Also at that time local manager Volpano was hired specifically to improve production and book international superstars on what was a mere Local Rock Stage, where then the Ramones, UFO, and Judas Priest headlined Live comedy acts have also been a part of Summerfest's history, even before a regular "Comedy Showcase" was first established in 1975. Bob Hope was the main headliner at Summerfest 1969, performing two shows at Milwaukee County Stadium. George Carlin (opening for Arlo Guthrie) performed his "Seven Words You Can Never Say on Television" routine at the 1972 event and was subsequently arrested