Blame Bill Millar. Although the English music critic had used the term throughout the Sixties, “swamp-pop”—a label everyone agrees is his invention—became ingrained in musicological lore forever with his 1971 essay in Britain’s Record Mirror, “Swamp Pop—Music From Cajun Country.” It wasn’t until the term was reintroduced via fellow Englishman John Broven’s 1983 book South to Louisiana: The Music of the Cajun Bayous, however, that Americans began to notice this uniquely Acadi...