Jack London is often pigeonholed as a literary naturalist, but his interests aligned with a science fiction tradition. Over the course of his career, London increasingly set his narratives in the ancient past and the distant future. These fictional temporal environments provided him with new vantage points with which to explore the political relationship between individualism and nationalism, an exploration that intensified in his later work. His little-known 1912 novella The Scarlet Plague, one of the earliest examples of postapocalyptic fiction, reimagined the western frontier in a new age. Its combination of a doomed heroic individual and a struggling Darwinian population set the tone for American postapocalyptic tales to come. An examination of this novella in its historical and compositional context reveals it to be a significant step forward in London’s literary development.