A new way is proposed to thermodynamically gauge the evolving complexity of nation-states and their growing cities. Energy rate density is a useful metric to track the evolution of energy budgets, which help facilitate how well or badly human society trends toward winning or losing. The fates of nations and their cities are unknown, their success is not assured. Those nations and cities with rising per-capita energy usage while developing and those that are nearly flat while already developed seem destined to endure; those with falling energy usage seem likely to fail. Globally, more energy, not less, and more energy rate density, too, will be needed in the 21st century. Conserving energy and efficiently using it are welcome since energy costs less when used less, but neither will likely help much to mitigate increasing energy demands. To survive, humanity nationally and internationally needs to culturally adapt to using more, clean, safe energy by embracing the Sun in an evolving Universe, where nations and their cities resemble galaxies and their stars as well as Earth and its life.