The set list leaned heavily on Kid Rock’s greatest hits, including a couple of classics from his first big album in the 1990s. If the musical vibe harked back to the days of Bill Clinton, the moment itself felt like a distillation of something very Trumpy. This was the “Rock the Country” tour, orchestrated by Kid Rock and unofficially promoted by the president to the duo’s overlapping fan bases. The result was a lively mashup of identity politics and beer-battered revelry that billed itself as “a gathering for the true heart of America,” where “hardworking, God-fearing patriots unite under the open sky.”