As rising seas, spreading wildfires, and unbearable heat shrink the expanse of the habitable earth, the prospect of a contracting world resonates in particular and forceful ways within the American imaginary. Recent American climate fiction responds to the specter of a shrinking world by reprising narratives of the American frontier, simultaneously unsettling and reanimating elements of these stories. This chapter pays attention to stories of neo-agrarian settlements, depictions of internal displacements and migrations, and portrayals of corporate collapse in the wake of dwindling carbon economies. It argues that American climate fiction can run retrograde, reiterating the very seizures of land and political suppressions that underwrote the American frontier. However, the radical environmental changes envisioned in this genre also intensify ongoing struggles for racial and economic justice in the United States, opening the possibility of more equitable forms of relation. Although the climatic future is often depicted as a brave new world, an unknown terrain, climate narratives must acknowledge rather than subsume history: A changed world must not be mistaken for a wholly new one.