Metal's roots may have come from the late '60s and '70s, but it can be argued that the genre's real coming out party happened May 29, 1983 at the US Festival in San Bernardino, Calif. The music weekend offered a wide array of musical options, with each day catered to a specific sound, but it was the Heavy Metal Day on May 29, 1983, that showed just how popular that metal had become.

The lineup featured home state rockers and rising stars Van Halen headlining the day, with Scorpions, Judas Priest (seen in the video above), Ozzy Osbourne, Triumph, Motley Crue and Quiet Riot filling out the bill. The bands represented on Heavy Metal Day were promoting such classic albums as 'Diver Down,' 'Blackout,' 'Screaming for Vengeance,' 'Bark at the Moon' and 'Metal Health' at the time of the event. The US Festival set a single-day concert attendance record with an estimated 375,000 people packing into the Glen Helen Regional Park near Devore, Calif. to see the show.

Ironically, the US Festival event was not a moneymaker, as Apple Computer honcho Steve Wozniak allegedly lost close to $20 million staging a pair of events in the early '80s. Part of that may have come from the exorbitant fee paid for the talent. It was reported that Van Halen commanded a $1.5 million payday to play the 1983 event.

Heavy Metal Day followed New Wave Day, which was initially expected to be the greater draw. The Clash, Men at Work, Stray Cats, A Flock of Seagulls, The English Beat, Oingo Boingo, Wall of Voodo, INXS and Divynyls all took the stage and while they earned a significant turnout, it was nowhere near what showed up for Heavy Metal Day.

Motley Crue frontman Vince Neil told, "It was the day new wave died and rock 'n' roll took over." Meanwhile, Quiet Riot's Frankie Banali stated via his band's Facebook page, "30 years ago today, on May 29, 1983, Quiet Riot performed at the US Festival on Heavy Metal Day, and that day proved to be a life changing experience for Quiet Riot, which I still feel today."

In all, over 670,000 people attended the four-day event that also featured a Rock Day and a Country Day, but over half of the attendance came from Heavy Metal Day, which provided the perfect measuring stick for exactly how popular the genre had become.

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