This study examines the artworks, letters, sketchbooks, music collection, and biography of the painter William Sidney Mount (1807–1868) as a lens through which to see the multiethnic antebellum world that gave birth to blackface minstrelsy. Christopher J. Smith uses Mount's depictions of black and white vernacular fiddlers, banjo players, and dancers to open up fresh perspectives on cross-ethnic cultural transference in Northern and urban contexts, showing how rivers, waterfronts, and other sites of interracial interaction shaped musical practices by transporting musical culture from the South to the North and back. The “Africanization” of Anglo-Celtic tunes created minstrelsy's musical “creole synthesis,” a body of melodic and rhythmic vocabularies, repertoires, tunes, and musical techniques that became the foundation of American popular music.