The relationship between the local and the global has long been a motivating question for US cultural studies. Any facile opposition between those categories is broken down by specific perspectives explored in literature, film, or music, and is surely complicated by quotidian and emplaced negotiations. The very question of "America" as nation or region, too, reframes any spatial inquiry. This essay engages these scalar and subjective dilemmas by focusing on the densely constituted worlds of racialized inhabitants of Harlem, a majority–minority space. A close reading of the 1934 short story "Spanish Blood" by Langston Hughes demonstrates the promise and perils of transnational blackness for author and represented subjects both. This little, understudied piece, I argue, illuminated big concerns: the intimate and tense relationship between African Americans and Puerto Ricans in urban areas, and the abiding anxiety of racial mixture. And conversations about blood and language in the story situated domestic relations in a broader field of global diasporas. The stakes of this analysis lie in the reimagining of Harlem's cosmopolitanism, a critique of discourses of sociospatial containment in urban life, and a careful consideration of the expanse of "Americas" studies.