Adapted from: E. J., Gauthier H. L. and M. E. O'Kelly (1996) Geography of Transportation.
Trade, Transportation and Geographic Specialization
The evolution of transport systems impacts the regional economy in terms of spatial specialization. The above figure represents a simplified example of how changes in transport may impact on the specialization of regional economies, which a priori have similar environmental endowments.
In a situation of self reliance there is no apparent transport link between two regions. They are isolated from one another and must satisfy their own needs. Each region thus tends to be similar in terms of economic output. While regions have different environmental endowments, they must still provide for every basic necessity such as food. Quantities produced depend on the demand and the industrial capacity.
With a transport link between two regions, specialization can take place. Each region develops its respective potential; Product A for the first region and Product B for the second, assuming that they respectively have a comparative advantage for these two products. If Product A is cheaper to produce in the first region, it becomes more efficient to lessen the production of other products and concentrate on Product A. Respectively, the second region can do so for Product B. Therefore, the first region can delegate more resources for the production of Product A which it can then sell the surplus (minus local consumption) to the second region. The key of this specialization becomes the difference between transport costs and production costs of a product. If the unit costs savings resulting from specialization exceed the unit transports costs, then specialization can take place.
Regional specialization is greatly expanded with international trade. By having access to a larger market through a gateway, namely a seaport, region A and B can specialize even more in the production they have respective comparative advantages on. They can even cease production in a specific array of products, which are now imported. Under such circumstances, the reliance on transportation increases, even if its relative costs may be declining.