The post–World War II United States witnessed a generation of artists, musicians, and performers eager to reclaim the arts on a global stage under the banner of “experimentalism.” This movement, most closely associated with John Cage’s circle and the downtown New York scene, tended to converge among other things around questions of “intermedia”—namely, how aesthetic experience emerges at the interstices between media, or how any seemingly singular medium engages multiple, interconnected senses and modes of perception. Such midcentury American preoccupations echoed late nineteenth- and early twentieth-century European legacies of aesthetic experimentalism across the arts, from Symbolism to Dada, which pursued a “unity of sense” and “personal and social transformation” via physiological aesthetics, as described by Robert Brain. Yet this midcentury American iteration of the “intermedial turn” also unfolded within a totally altered global political environment of Cold War cultural competition, with New York artists seeking to inherit a mantle of cultural leadership from the old metropolises of Europe. Within this setting, the downtown New York milieu often tended to eschew strong claims of European patrimony in favor of American exceptionalist ones. Indeed, by the late 1950s “American experimentalism” emerged as a robust and contested project of national canon formation in the arts. Ambivalently entangled with assertions of American scientific and technological primacy, its intermedial explorations benefited from the new affordances of postwar computing and electronics. My project excavates the history of this intermedial turn within American experimentalism with special attention to processes of migration that shaped mid-century New York creative scenes, including the early performance and conceptual art movements, Fluxus, and the Columbia-Princeton Electronic Music Center.