Many of the ideas that most influenced the design of cities were first expressed through diagrams. These simple visual statements have become iconic distillations of values, policy agendas and ideologies — touchstones in the visual lexicon of urban planning and design. Grand Reductions: 10 Diagrams That Changed City Planning investigates the visual culture and iconography of city planning and the impact, for better or worse, of these ideas on the shape of communities in the United States.