The Rediscovery of Geography -- Linkages and Circular Causation -- Modeling Tricks: Dixit-Stiglitz, Icebergs, Evolution, and the Computer -- Some Intellectual Background -- Antecedents I: Urban Economics -- The von Thunen Model -- Explaining Cities: External Economies -- Urban Systems -- Multiple Subcenters -- Uses and Limits of Traditional Urban Economics -- Antecedents II: Regional Science -- Central-Place Theory -- Base-Multiplier Analysis -- Market Potential Analysis -- Limitations of Regional Science -- A Brief Introduction to Bifurcations -- Labor Mobility and Regional Development -- The Dixit-Stiglitz Model of Monopolistic Competition and Its Spatial Implications -- Consumer Behavior -- Multiple Locations and Transport Costs -- Producer Behavior -- Some Normalizations -- The Price Index Effect and the Home Market Effect -- The "No-Black-Hole" Condition -- Core and Periphery -- Instantaneous Equilibrium -- The Core-Periphery Model: Statement and Numerical Examples -- When Is a Core-Periphery Pattern Sustainable? -- When is the Symmetric Equilibrium Broken? -- Implications and Conclusions -- Symmetry Breaking -- Many Regions and Continuous Space -- The Three-Region Case -- The Racetrack Economy -- The Turing Approach -- The Growth Rate of a Fluctuation -- Determining the Preferred Frequency: The Large Economy -- From Local to Global -- Simulation Parameters -- Agricultural Transport Costs -- Trade Costs: The Realities -- Trade Costs: The Model -- Core-Periphery or Symmetry? -- Differentiated Agricultural Products.