There are a few South Park episodes on the matter. Like "I'm a Little Bit Country", where there is an argument on if South Park should go to war or not. Here's an actual quote from the episode:
News Reporter: Tom, I'm standing in the town square where the war rally has been going on for an incredible eighty-seven hours. The crowd still appears to be split right down the middle - half of them support country music, and the other half rock-n-roll.
According to
South Park Scriptorium, "The music genres were chosen because a lot of rock musicians are anti-war, and most country musicians are pro-war. The accompanying stereotypes shown are that country fans are poor, simple, and uneducated, while rock fans are rich, sophisticated, and educated."