10.9: Central Place Theory and Urban Morphology

Central Place Theory

In regions where no single location has special site location advantages situation advantages become very important. This happened on the vast plains of the United States during the 1800s, in places like Kansas where there are few navigable rivers, waterfalls, or ports. In instances like this, situation advantages become supremely important and generally a predictable, geometric pattern of cities and towns and villages tends to emerge. This process was more pronounced when transportation was primitive and the friction of distance was great, making the outcome of this process visible on the map of many flatland regions of the earth. Geographer Walter Christaller noticed the pattern and developed Central Place Theory to explain the processes that produce this pattern of cities, towns, and villages.

Figure Central Place Theory. This diagram represents an idealized urban hierarchy in which people travel to the closest local market for lower order goods, but must go to a larger town or city for higher orders goods.

According to Christaller, if a group of people diffuses evenly across a plain (as homesteaders did when Kansas opened for settlement), a predictable hierarchy of villages, towns, and cities will emerge. The driving force behind this pattern is the basic need everyone has for goods and services. Naturally, people prefer to travel less to acquire what they need. The maximum distance people will travel for a specific good or service is called the range of that good or service. A product, like a hammer, has a limited range because people will not travel very far to buy hammers. A tractor, because it is an expensive item, has a much greater range. The cost of getting to a tractor dealership is small compared to the cost of the tractoritself, so farmers will travel long distances to buy the one they want. Hospital services have even greater ranges. People might travel to the moon if a cure for a deadly disease was available there.

Merchants and service providers also require a minimum number of customers living within a range to stay in business. Christaller called this number the threshold population. A major league baseball team has a threshold population of around two million people living within the range for a major league baseball franchise (the Milwaukee Brewers have the smallest local market at around 2 million people).A Wal-Mart store, on the other hand, has a minimum threshold of about 20,000 people, so they are far more numerous. Starbuck’s Coffee shops have a threshold of about 5,000 people, and a range of a few miles, therefore they are numerous.

As customers and merchants living and working interact over many years in a flat region like Kansas, businesses in more centrally located villages will attract more customers because of the convenience of their location. This allows those businesses to grow and thrive. Additional businesses, and customers, are therefore attracted to those villages and over many years, those villages grow into towns or even cities. Less conveniently located villages will not attract customers, nor retain merchants, and they will not grow. Competition between towns prevents neighboring locations to grow large. As a result, centrally located villages tend to grow into larger cities at the expense of their neighbors. A network of centrally located towns tends to emerge in a geometric pattern, and among those growing towns, a few will grow into large cities.

Mulligan, Gordon F. "Agglomeration and central place theory: a review of the literature."

International Regional Science Review 9.1 (1984): 1- 42.

The largest cities will have businesses and

functions that require large thresholds (like

major league sports teams or highly specialized

boutiques). Merchants in villages and small

towns offer only the most basic goods and

services (e.g., gas stations or convenience stores)

forcing villagers to travel to larger cities to buy higher-order goods and services. Some goods and services will be available in medium-sized cities, often called regional service centers. Some goods and services are only available at the top of the urban hierarchy; the mega-cities of the world. In the United States, a handful of cities (New York, Los Angeles, Chicago, Dallas) may offer exceptionally high order goods, unavailable in other large cities like Cleveland, Seattle or Atlanta.

Figure Map of Lamborghini Automobile Dealerships in the United States. Expensive automobiles have limited thresholds and extensive ranges, therefore only very high order places host such businesses. Source: Lamborghini

Central Place Theory is one of the more compelling and widely applied theories in geography. It’s not perfect because it is a model, and many criticisms have been leveled at it, but it can be successfully used to explain a great number of locational tendencies evident on the landscape.

Urban Morphology

You’ve probably visited several large cities and noticed how differently they are organized. Visits to new cities can be disorienting if you’re not used to the layout of another city. The way a city is organized in space is called urban morphology, and each city’s layout offers strong clues into the evolutionary trajectory of the city. The morphology of a city is also a very potent force acting upon the cultural, political, and social life of each city.

Figure San Francisco, CA. Public rail transportation has a significant effect on the evolution of cities. The extensive rail system in the Bay Area has played a substantial role in the development of the personality of Bay Area cities like San Francisco.

Consider for example, how the Californians often talk about the radical differences between Los Angeles and San Francisco. The differences are partly the by-product of the migration streams that populated each city generations ago, but profound differences in the basic physical geography of each city have also led to very different urban morphologies. A recursive relationship between each city’s urban morphology and its political culture seems to have led to significant differences in the public transportation, housing, culture and politics of San Francisco and Los Angeles.

During the early 20th century a number of geographers, sociologists, and anthropologists trying to understand how cities worked, developed a variety of models to help identify, describe, and explain the various urban morphologies evident in the US and beyond. Many of these models were created by scholars at the University of Chicago, a city that had undergone incredible growth in the previous century.