Often focused on the rapid development of technologies (both scientific and social) and their dangers, American science fiction (SF) novels have highlighted how the twentieth century is characterized by truly global crises and possibilities, from the mass migrations and their various exploitations in the early twentieth century, to the Cold War and the direct threat of global nuclear destruction, to giving voice to those denied rights and silenced both in the earlier SF canon and in the larger body politic, and to the climate emergency. Distancing these political issues from the real, twentieth-century SF novels may risk making specific political moments seem fantastic, but they can simultaneously enable new forms of global and communal visions that are (increasingly) necessary to political action. To discuss these visions, the chapter discusses a range of different traditions running through SF and parallel forms of work throughout the twentieth century, with a particular focus on the role of Black and Afrofuturist writers in the period.