Urban Hierarchy
There are two main paradigms in which an urban hierarchy can be represented:
  • Christaller Model. According to this model, a dominance is established between several orders of the hierarchy. This relationship implies that a center of a lower order must rely on a center of higher order for goods and services not being locally supplied.
  • Pred Model. Christaller's model was adapted by Pred to become more flexible and to reflect more complex interactions. First, centers of the same order are not necessarily at the same hierarchical level. This shows that some centers offer more diversified goods and services than other centers, even if they are of the same size population-wise. Interdependency implies that central places can exchange similar goods and services since they are competing in an open market allowing several producers. Complementarity enables several centers of a similar order to specialize in specific activities and be supplied in goods and services they do not have from other centers. This implies the notion of economies of scale reinforcing a regional specialization.