Beyond its south Louisiana birthplace, swamp pop is less known than the region’s internationally branded Cajun and zydeco music. A hybrid of Cajun-French music and classic rhythm and blues from New Orleans, swamp pop is most of all music made for a dancehall on a Saturday night. Singer-songwriter Yvette Landry grew up in a swamp pop–loving family in Breaux Bridge. She heard Cajun music on the radio, but swamp pop, not walt...