The third factor necessary for interaction to take place is the absence or lack of intervening opportunities. There may be a situation where complementarity exists between an area with a high demand for a product and several areas with a supply of that same product in excess of local demand.
In this particular case, the first area would be unlikely to trade with all three suppliers, but would instead trade with the supplier that was closest or least costly. In our example of the trip to Disneyland, "Is there any other destination theme park identical to Disneyland, providing an intervening opportunity between San Francisco and Los Angeles?" The obvious answer would be "no." However, if the question was, "Is there any other regional theme park between San Francisco and Los Angeles that could be a potential intervening opportunity," then the answer would be "yes," since Great America (Santa Clara, California), Magic Mountain (Santa Clarita, California), and Knott's Berry Farm (Buena Park, California) are all regional theme parks located between San Francisco and Anaheim.
As you can see from this example, there are numerous factors that could affect complementarity, transferability, and lack of intervening opportunities. There are many other examples of these concepts in our daily lives, when it comes to planning your next vacation, watching the freight trains roll through your town or neighborhood, seeing the trucks on the highway, or when you ship a package overseas.
Brett J. Lucas graduated from Oregon State University with a B.S. in Geography, and California State University East Bay, Hayward with a M.A. in Transportation Geography, and is now a city planner for Vancouver, Washington (USA). Brett developed a strong interest in trains at a young age, leading him to discover hidden treasures of the Pacific Northwest.
