Historians of agriculture have not spent enough time thinking about energy, and historians of energy have not spent enough time thinking about agriculture. During the second half of the twentieth century, farmers transformed the High Plains of the United States into a nonrenewable landscape. Using one nonrenewable resource (fossil fuels) to exploit another (ancient groundwater), farmers broke the ecological constraints of the region’s semiarid environment and dramatically boosted cropland productivity. The development of North America’s largest natural gas field made abundant and cheap fossil fuel energy available to farmers, who adopted energy-intensive center-pivot irrigation systems. High cropland productivity attracted the cattle feedlot industry, which produced profits for farmers but an incredibly low energy return on investment. Fossil fuels provided the energy farmers needed to lift the enormous volumes of water necessary for industrial agriculture on the High Plains. Farmers made decisions based on water, but those decisions were fundamentally structured by energy.