America and the Rockstar Energy Mayhem Fest? Was this the best Fourth of July ever? As the sun rose on a gorgeously temperate (compared to SLC, that is) summer day in Nampa, Idaho, it was hard to imagine a better one. I couldn’t help but feel the excitement build as I watched bus after bus wheel up to the Idaho City Center amphitheater. Motörhead, Slayer, Slipknot, Anthrax. It was gonna be a hell of a day.