At the Bering Straits, Russia and Alaska share a common ecology: rolling tundra and icy mountains divided by the narrow ocean. Every living thing exists without plentiful solar energy, curtailing the productivity evident in temperate climates. Yet over the course of the long twentieth century, Russians and Americans were drawn north by its potential riches, from the energy in walrus blubber to the currency of gold. They stayed to make converts, fortunes, and states. This dissertation chronicles the environmental, political, economic and cultural revolutions that came in their wake. These revolutions map onto the distribution of energy in arctic space. Europeans began by harvesting whales, moved to hunting walrus on coasts, attempted to farm reindeer on land, sought gold underground, and finally returned to hunting whales at sea. Organized around these spaces, the following five chapters trace a narrative from the stateless meetings of indigenous Yupik, Inupiat, and Chukchi with commercial hunters, to the inception of national borders and ideas of citizenship, through to the region’s division along ideological lines. Using ecological and anthropological scholarship and sources from twenty local, regional, and national archives in the U.S. and Russia, it examines how capitalism and communism, which imagine history as universal, progress as inevitable, and production as infinite, met with the constraints of the far north. The common extremity of the Beringian environment provides a unique space in which to compare the twentieth century’s two great economic systems. The resulting insights transcend the peripheral geography, and contribute to major questions in the histories of capitalism, socialism, and the environment. First, comparing how people understood their northern environs, and how they chose to change them, demonstrates how both economies were laced with normative assumptions about the trajectory of people’s lives and history. Capitalism was never simply about how commodities were owned and traded, any more than communism was only about collective ownership of the means of production. Rather, both were ideologies that shaped what was thinkable, valuable, and rational. Second, these ideas did not exist outside environmental context. In ways specific to marine, coastal, and terrestrial habitats, local ecologies changed the practice of communism and capitalism. By investigating how intent became action, and action shaped new intents, this project shows instances of socialist rationality, market irrationality, and unexpected resemblance. Above all, both economic and ideological systems were contingent on factors beyond human control. Attention to the non-human, from animal behavior to climate, demonstrates how agency, in the sense of individual or collective will working on the world, was situational. The result is a history of how human intention and action were negotiated in concert with the environments they inhabited.