The swamp blues have lain in the margins of music history despite foundational, if brief, contributions to 1960s popular music broadly and British blues-rock specifically. The canon is not stylistically unified, but organized around a musical sodality from the independent record industry of Southwest Louisiana between 1954-1966. Why has this regional music been forgotten, and why are the few traces of its history all overseas? Through an investigation of the postwar industrial and economic forces that reshaped the South Louisiana cultural territory into a Southeast-Texas-and-Southwest-Louisiana musical byway, this dissertation reveals how migrations of African-American workers and a “Crawfish Circuit” of nightclubs heightened musical exchanges across the region. Influenced as much by New Orleans’ piano-driven r&b as Texan guitar blues, the swamp blues represent a cultural third-space beyond the more popular Zydeco and swamp pop local arenas. Poppy, sophisticated, grooving ensemble r&b by Charles Sheffield, Katie Webster, Lionel Prevost, and Slim Harpo, late-era downhome blues by Lightning Slim and Juke Boy Bonner, and transitional r&b that encapsulates both sides from Guitar Jr., Big Chenier, and Lazy Lester came out on Excello and Goldband Records. The music trades alternately in notions of downhome authenticity and hip urbanity, the anticommercial and the big-league professional. Under the black-white binary aegis of the postwar record industry, non- Creole African Americans here made trendy records with vast market appeal, all sourced from Louisianian musical crossroads and material, and in so doing, harnessed essentialist ideas about black American identity to commercial ends. Few swamp blues musicians had virtuosic talent, so history has instead honored the genius of two white independent record producers, J.D. Miller and Eddie Shuler. Their watermark follows the swamp blues overseas, where a British fanbase buoyed the Jay Miller legacy especially. I consider how, across different spaces in time, the placedness of black musicians’ bodies has influenced varying interpretations of the swamp blues. I argue that the unconventional “regional” swamp blues beg a revaluation of both blackness in Civil Rights-era Southwest Louisiana, and the accepted racial and ethnic segregations of sound found there that exclude the swamp blues from standard narratives of local music history.