Urban Geography Reading 02
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Theories On How Cities Develop and Grow
In this reading you will learn about a number of ideas that geographers used to help explain why cities grow. There are almost as many theories as why cities develop and grow as there are geographers. However, we will concentrate on a few of the older and more established theories as to why cities grow.
First, we must explain some things about cities that will help prepare you for our discussion of city growth. The basic function of a city is to assemble, process, store, and redistribute goods, peoples, and ideas. This function attempts to overcome the problem of resource distribution. The distribution of resources over the landscape is not even. Resources (food,gas,labor) are never located where you want them, when you want them. Cities attempt to bring together all of the resources for production or living that a person would need. The more able a city is to solve the problem of resource distribution, the more attractive a city will be to live in, work in, and play in.
Definitions of the term "city" vary, but generally a city is a large settlement whose inhabitants carry on a variety of activities that are not related to agriculture. In some parts of the world, the term has more specific meaning as well. In the United States, localities with populations of 2,500 or more are defined as urban, which means "characteristic of a city". In Japan, a settlement must have a population of at least 30,000 to be considered a city; in Sweden, a densely settled population of 200 is enough. In the United Kingdom, "city" is a title given to towns that historically served as religious centers or were honored by a special act of the Crown. For most purposes, though, the term "city" can be used to describe almost any urban center in the world.
All Cities share certain characteristics. They are densely populated, and their inhabitants hold a wide variety of jobs requiring specialized skills. City dwellers depend upon one another for services and for survival in a complex way of life. Communication and cooperation among residents are essential if a city is to function smoothly.

The Van Thuen Model (A graphic of the Van Thuen Model is located here)
One theory used to explain how cities develop is called the Van Thuen Model. This model was set up in an imaginary world. This world had only one state with one city located at the center of this state. Van Thuen then said that their were rings, like rings around a bullseye on a target, that spread out away from this central city. Van Thuen said that as you moved out into each ring, farther and farther away from the central city, the cost of transportation of goods would go up and the cost of land would go down.
Van Thuen broke the rings up into the following zones of land use; in the center was the city or marketplace, next out was the zone of intensive farming, third was the forest area, fourth was the region of extensive farming, fifth was the zone for ranches, and lastly was the wilderness that separated the city and its zones from the rest of the world. (see chart number one)
Why did Van Thuen brake up the zones in this fashion? he believed that the cost of land and transportation would break the zones up along these lines. Intensive farming was in the second zone because items like dairy products, products that perish easily, had to be grown near their market. Also, any product that could bring a large profit, was grown in this second zone. Because the land in this zone was so accessible to the central city, the cost of land in this zone was very high.
The third layer out was called the Extensive farming zone. This zone was where crops like corn and wheat were grown. In order for the farming of these crops to be profitable, they must be grown on large tracts of land, therefore farmers that grow these crops are using sections of land much larger than those found in the Intensive farming zone. Transportation costs are higher in this region, but the quantity of the product helps spread out the overall cost of transportation. Eventually, the cost of transportation cannot be spread out enough over the quantity of the product grown and farming of this type will cease to be profitable. At that point, ranching will begin to occur.
Ranching is the fourth ring in Van Thuen's model. Ranching requires an enormous amount of land for all the cattle needed to make a ranch profitable. Because of the enormous amount of land required, ranching is the farthest out in Van Thuen's model.
Beyond the ranching ring in the model, there is nothing but wilderness, it is not profitable for any economic activity to go on this far away from the central city or marketplace and still overcome the cost of transporting goods to market.
We can learn two geographic principles from Van Thuen's model; first, the more land required to make an operation profitable, the farther away from the city center it will be located. Secondly, the size of the operation must be balanced with the cost of transportation.

The Concentric Ring Theory
The Concentric Ring Theory expanded on the idea of zones of economic activity. This Theory was put forth during the 1920s. Since that time, other theories have come forth to try to explain in greater detail the pattern that cities follow when they grow.
The Concentric Ring Theory used the ideas of zones to explain how cities grew (see chart number two). This theory, like the Van Thuen Model, believed that the cost of land went down the farther away from the Central City or market place that you were located. This theory also believed that the cost of transportation went up the farther away from where you were located from the Central City.
The Concentric Ring Theory called the Central market place the Central Business District (CBD). Inside this CBD, land was incredibly expensive and only businesses that could afford to build tall skyscrapers to overcome the cost of land, could afford to locate in this zone.
The next zone was low rent housing zone. These low rent buildings were built very close together and built many stories high so they could house many renters. The people who lived in these apartment buildings could not afford the cost of transportation to the outer zones to live. The people who lived in this district walked to work in the CBD.
The next zone out was called the working class zone. For the most part this zone was filled with apartments of higher cost filled with people who worked in the CBD and could afford the cost of mass transportation to the CBD and housing farther away from the CBD. In some instances, workers in the zone owned their own homes.
One of the ideas that pops up at this time is the notion of neighborhood. A neighborhood is a residential area where people live near, and interact with, one another. Usually neighborhoods are in cities, although they may be found in rural areas as well. Their geographic boundaries are often loosely defined.
Residents of urban neighborhoods often share the same concerns and values. They are generally have similar incomes as well as similar social characteristics such as education level and housing preference, and a similar sense of public order. The most familiar type of neighborhood is the ethnic neighborhood, an area where people with the same cultural background choose to cluster together to live. This strengthens their sense of community and preserves cultural traditions. Residents benefit from nearby relatives, common language, stores and services geared to their needs, and institutions important to them, such as churches and clubs. Unlike neighborhoods, ghettos historically have been areas where ethnic groups have been forced to live.
The fourth layer in the Concentric Ring Theory is the Better Homes district. This district has home owners that can afford the cost of land so near the CBD. These homes are the most expensive in the Theory. The people of this zone are the higher level managers of the CBD. They commute to work in their own vehicles. Often the homes in this zone are large, with equally large amounts of land surrounding them. It would be right to describe this as the wealthy part of town.
The fifth layer in the Concentric Ring Theory is the commuter zone. People in this zone own their own homes and commute by car great distances to work. The people of this zone, can afford the cost of transportation into the CBD, but not the cost of land in the Better Homes zone. The people in this zone are the middle level management people of the CBD.
If the Concentric Ring Theory was correct, every City in the world would look like a big target. Being that this is not true, there are other factors that go into determining the size of cities. Some of those factors will be discussed in the next section of this reading.

Factors That Affect City Size
There are many factors that affect city size, two of the most important are site and situation. Site is the actual physical geography of the setting, and this includes the topography, water, climate, and pathways that line the site to other places. Situation is the relationship of the site and its population to other locations. As we look at other factors that affect city size don't forget, Site and Situation are the two most important and overriding factors that affect city size.
The next level of importance when determining factors that affect city size are as follows; age of the city, location of the city on an ocean or river, whether or not the city is a transportation center, the level of mass communication that occurs in the city, and technological improvements that make living in the city easier than it would be without the improvements.
The age of a city can affect its size more than anything else. Being first is sometimes all it takes to be the largest. Think back to our reading about the history of the city, many of the cities mentioned in that reading are cities that are still very important in the world today.
Being a good, natural harbor on a river or ocean is a second factor in determining the size of a city. Of the 37 largest U.S. cities, only 7 are not located on a river or large body of water.
Thirdly, being a transportation center can greatly help a city become large in size. Some cities like Denver, Chicago, and Atlanta were very small towns until they became railroad centers. Later, the people who ran these cities were smart enough to make sure that they also became major centers for air transportation. Today, Denver is making a new airport. This airport will be one of the largest in the world. This airport will be the first in the nation to be able to handle the next generation of airliner, the Hypersonic jet. What kind of advantage do you think this gives Denver in the 21st century?
Mass communications plays a major role in allowing the city sending out information to better advertise itself to the world. Think how well Los Angeles has been able to advertise itself during most of this century because of its connection with Hollywood. Where are the three major TV networks located? New York, think how that helps New York broadcast its message to the world.
The last major factor to mention is technological improvements. This factor is very subtle but, very important when determining factors that affect city size. The first example of a technological improvement is the elevator. How tall do you think buildings would be if it was not for the invention of the elevator? Another technological improvement is the air conditioner. How many people do you think would want to live in Phoenix in July when it hits 120 degrees, if there were no such thing as an air conditioner?
To show you how important technological improvements can be to the growth of a city, I'm going to introduce to the theories of a man named John Adams. Mr. Adams calls his theory, The Stages of Intraurban Growth.

The Stages Of Intraurban Growth
Mr. Adams said there were four stages of Intraurban growth; the Walking/Horsecar Era, the Electric car Era, the Recreational Auto Use Era, and the Freeway Era. Each of these eras allowed cities to grow out further away from the CBD and become larger because of the different inventions that changed personal mass transportation.
The Walking/Horsecar era was the period of time up until the invention of the electric traction motor in 1888. Most people got around on foot. After about 1850, horsedrawn carriages could take people around but the speed of these carriages was only about six miles per hour. Most urban dwellers got around on foot, and most of them travelled less than 30 minutes to get what they needed. Cities were crowded into a small space and there was very little specialization of land uses.
After the electric motor was invented in 1888, Electric horse cars could carry people around at top speeds of up to 20 miles and hour. This allowed people to expand their 30 minute travel distance. Urban areas expanded out from the CBD along these electric trolley routes. In some cities, land used differences were beginning to show up.
The electric motor era lasted until about 1920, when the mass produced automobile started to change the way Americans got around. The ability of people to travel beyond the outer edge of the previous city limits allowed for the "suburbanization" of American cities. The half hour travel distance increased again. Slowly but surely fully defined neighborhoods divided by race, ethnic background, and income began to appear all over the urban landscape.
Shortly after World War Two, American urban life entered the Freeway era. Freeways allowed commuters to live 30 miles or more away from the CBD as urban development followed the freeways out into the suburbs. Old Central Business District businesses and services moved out to the suburbs with the people. Suburbs began to develop their own ways of attracting business and customers to what formerly was "out in the country". By the mid-1950s, shopping centers and malls were starting to replace some of the services customers went into the CBD to buy.
You have now read about some of the factors within the city that help it grow and develop. With the next reading, you will learn about some of the factors that affect patterns between cities. You will also learn about the network that connects cities to one another.

References and Acknowledgements
Site and Insight; Kit Salter
Regions and Concepts; Harm de Blij and Peter Mueller
Exploring Your World, Adventures in Geography; The National Geographic Society
The lectures of Dave Lanegran and Jerry Pitzl during the 1986 Summer Institute at Maclester College in St. Paul, Mn.
Thank you Gene Ullenhopp,Steve Slakey, Bob Marcotte, and Dick Bernard