The arid border region that encompasses the American Southwest and the Mexican northwest is an area where the nexus of water scarcity and climate change in the face of growing human demands for water, emerging energy scarcity, and economic change comes into sharp focus. Day et al. (2016a) discussed these interacting problems for the American Southwest and focused on Los Angeles as an example of these problems. They concluded that the region “bloomed” with the coming of cheap fossil fuels that allowed the development of a sophisticated but expensive water supply system that supported a modern technological society. But society is entering a time of both water and energy scarcity that will challenge the region as never before. The Colorado River is the most important water source for this region. It is a shared resource that is used by other southwestern states and México for human consumption and agriculture. The two countries in this region are linked not only by water but also by strong economic ties and cross border population movements.