It is not simply that these two cities are perched side by side at the edge of the Pacific; it is that adolescence sits next to middle age, and they don't know how to relate to each other. In a way, these two cities exist in different centuries. San Diego is a post-industrial city talking about settling down, slowing down, building clean industry. Tijuana is a preindustrial city talking about changing, moving forward, growing. Yet they form a single metropolitan area.