THE URBAN SYSTEM

1. THE URBAN SYSTEM CENTRAL PLACE THEORY and RELATED CONCEPTS

2. The US at night

3. Is there an order to this? Maybe it’s an underlying geometry in the settlement pattern…

4. Is there an order to this? Maybe all we need to do is rearrange the cities slightly to make the pattern apparent.

5. OBJECTIVE • to understand the dynamics shaping the urban hierarchy • what makes cities grow quickly or slowly? • how do urban settlements of a particular size affect the emergence and growth of other settlements of the same or different size? • what pattern would the system of settlements form in the absence of complicating factors such as topography and history?

6. Why ask these questions? • to advance toward a more scientific understanding of urbanization • to develop a foundation on which to build a positivist theory of urban growth • to “raise” urban studies to the “level” of the hard sciences--assuming the hard sciences are superior to the soft (humanistic, descriptive, probabilistic) sciences

7. Every science needs a force … • economic competition • between cities • rational maximization • by individuals • friction of distance as a driving force • cost distance • time distance • (later) cognitive distance

8. In short… • Through rationally maximizing the productivity of their time… • by minimizing the costs of various activities measured in money and time, • people collectively create a system in which facilities of all sorts… • including cities, • are pitted against each other… • and all facilities emerge from this competition in advantageous locations and with predictable-sized areas of dominance.

9. Competition Produces Order In other words …

10. Founders of Central Place Theory • C.J. Galpin (1915) • sociologist studying rural communities in Wisconsin • decided that under ideal conditions settlements would be spaced evenly • pattern: overlapping circular service areas with the central places aligned in a hexagonal array • overlap of service areas indicates a region in which a person is equally inclined to shop at either central place

11. Galpin’s model

12. Founders of Central Place Theory • Walter Christaller (1966) • assumption: each good has its particular range and threshold • threshold of a good: minimum size of market capable of sustaining a business devoted to that good • range of a good: maximum distance a person will be willing to travel to obtain that good • associated assumptions • variations in range and threshold from person to person or from culture group to culture group are irrelevant • most people will shop at only one center

13. Details of Christaller’s theory • The vast range of retail functions could be grouped into 7 “orders,” corresponding to cities with different sized hinterlands • the functions in an order share a similar threshold and range • automobiles would be in a different order than loaves of bread, for example • What might be in the same order as automobiles? • What might be in the same order as loaves of bread?

14. Hypothetical pattern of central places

15. More terminology • “Higher order” goods and services are those with a wider range and higher threshold, located in larger urban centers • “Lower order” goods and services are those with a narrower range and lower threshold, located in smaller urban centers • “break point”: the invisible boundary between markets of competing central places • “isotropic plain” uniform land surface on which these ordering principles would generate a hexagonal pattern of cities

16. An interpretation of the urban hierarchy (listed by order) • largest cities (all functions, highest to lowest) • large cities • small cities • larger towns • smaller towns • villages • hamlets (only the lowest order functions)

17. Variations on the basic theory • different patterns result from different values of k • market optimizing, k=3 (minimizes total number of settlements serving a region) • traffic optimizing, k=4 (emerges by minimizing the road lengths joining all adjacent centers) • administration optimizing, k=7 (assumes lower-order places must be contained in the administrative districts of higher order places; can not be situated on the breakpoint)

18. Market principle (a) and transportation principle (b)

19. Market principle Transport principle Administrative principle

21. The US at night

22. Cool idea, not much basis in reality • cities just don’t form these patterns • they do respond to some kind of hierarchy-forming process, however • evidence: • the rank-size distribution • alternative explanation: • connection rather than competition: the power function law of networks

25. Founders of Central Place Theory • August Lösch (1954) • similar to Christaller’s theory but without the classification of urban functions into a finite number of orders • implication was that cities could be any size and would form a continuous distribution of sizes

26. Power laws and scale-free networks Recent research on networks of various types (Internet, neural networks, social networks, electrical grid, ecological systems, biochemicals, brains) has revealed that the hierarchy of node degree consistently follows a power law relationship: straight line on a log-log graph.

27. What would this indicate? • Urban hierarchy’s regularity may not be caused by the random perturbation of what would ideally be a step-wise function caused by competition between cities • Instead, it may be caused by the natural emergence of dominant (hub) nodes within a dynamic network