Preview this course
The American City, Part 3: Learning from the Grid
Already a subscriber?
The American City, Part 3: Learning from the Grid

The American City, Part 3: Learning from the Grid

54 min
Credit: AICP CM

This course is approved for 1 AICP CM credit

The course is about the formal composition and spatial process of the American urban grid. The course demonstrates a well-defined spatial logic to how American cities tend to evolve over time, conserving the importance of the "center" (e.g., historical area and/or Central Business District) in relation to the ever-expanding edges. By understanding these concepts, we can better understand how "bedrock" urban attributes (such as block size and dwelling entrances) and common growth trends (such as strip malls and leapfrog development) play a role in the spatial logic of American cities.

The objective of this course is to better understand the spatial implications of design decisions when intervening in the American city.

In This Course

  1. There is a well-defined, mutually supportive relationship between formal composition and spatial process in the urban grid of all cities during growth. The real strength of American cities lies in the historical use of regular grids, making this variety of "organized complexity" more readily apparent to the naked eye than older models of urbanism.
  2. Street Extension
    This chapter introduces the concentric zone and sector models of city growth and explains the basic features of linear or street extension in settlement form. The instructor also explains how small settlements tend to coalesce around the elemental cross-axis described 2,000 years ago in Roman regular grid planning.
  3. The Shifting Center
    This chapter introduces the phenomenon of the "shifting center" in settlements, which is rooted in growth of the ever-expanding edges of urban grid. The instructor also demonstrates the problem of grid expansion in how visibility and distance are mediated in the street network. The "shifting centers" of Savannah, Fernandina Beach, and Chicago are examined.
  4. Grid Deformation
    Grid deformation usually occurs due to an external factor—most often, local topography and land ownership. "Seam streets" between offset grids tend to become functionally important streets in such settlements. Seam streets may extend into the periphery during urban growth to become the organizing mechanism of peripheral growth.
  5. Block Manipulation
    Block manipulation, which conserves the old center of settlements, can be used to mediate the phenomenon of the shifting center. An examination of Philadelphia demonstrates block subdivision played a vital role early in its history. American regular gridded cities tend to simultaneously amalgamate toward and fragment from their preconceived formal order over time. In many cities, these spatial processes work together in giving rise to an emergent ortho-radial grid over time.
  6. Principle of Centrality and Linearity
    There is constant tension in cities because the most compact, internally accessible shape is a circle and the most extensive, externally accessible shape is a line. These diametrically opposed properties are the basis for Hillier’s principle of centrality and linearity. The most basic features of this principle in cities are blocks and streets. This chapter examines the historical growth of New Haven from 1638 to 1862 to show how the processes of street extension, block manipulation, and grid deformation worked together to resolve this tension and give rise to an ortho-radial grid.
  7. When Is a Door More Than a Door?
    This chapter examines the historical growth of Savannah, Georgia from 1733 to 1856. The ward concept is a synthesis of the Vitruvian and Alberti/Spanish plan concepts, but with a distinctive American twist (elongated blocks), which has led to some confusion about how the ward plan actually works. The instructor explains why the third dimension of building in Savannah, the location of dwelling entrances, compensates for the "shifting center" in the orthogonal grid logic of the ward plan.
  8. Leapfrog Development
    This chapter briefly explains leapfrog development and the multi-nuclei model of city growth. The instructor argues that the multi-nuclei model of city growth is ex post facto urban theory for the practice of Euclidean zoning in the post-war period. Leapfrog development represents a simple, economic transaction: buy cheap agricultural land now, improve the land, and sell more valuable urban land later to profit on land appreciation. That process is fed by Euclidean zoning.
  9. Discrete Separation
    This chapter explains the spatial process of discrete separation by linear segregation in post-war suburbs. The instructor also discusses the consequences for city centers, ring roads/orbital highways, alternative public transportation, and the American lifestyle.
  10. The Block, Street, and Network
    This chapter concludes the course by addressing implications for urban theory and public policy.