This is RPG-ology #13: Cities, for December 2018.
When I wrote about Country Roads I promised to return at some point and write about city streets. However, as I thought about it, I realized that before you can understand city streets, you have to understand cities–why they exist, why they form where they do, and what factors govern their patterns. So this is a look at cities; we’ll come back to the streets another time.
There are two general categories of reasons for cities to come into existence, which we can identify as commercial and governmental, and a few subcategories of those that have some impact on them.
The primary commercial reason for the appearance of a city is resources. Chief among these are those related to water, in three distinct ways.
Cities grow at natural harbors, because of shipping. Thus on oceans, but also on inland seas, huge lakes, and deep rivers, trade begins, shippers move goods in and out, and a city is built around the income from transportation. Whether it is triremes bringing goods in and out of Greece, galleons carrying gold from Mexico to Spain, steamboats on the Mississippi, or oil tankers running between Kuwait and Perth Amboy, more goods move farther by water than by any other mode of transport, so where there is a convenient place for ships to load and unload, a city will form.
Water is also a necessity of survival. Great cities don’t generally form spontaneously in arid deserts, unless there is a reliable water source available. People need water to drink, but also to raise crops and livestock, to wash, and for a wide variety of industrial purposes from making paper to cooling nuclear reactors.
Water is also one of our earliest sources of power after slaves and draft animals. Water turning wheels drove early mills for grinding grain, and eventually drove machinery that wove cloth and created many other products. Today, at least part of our electricity is generated from moving water.
Thus if you have a natural harbor, or a river or large lake, or even a spring, it can become a reason for a city to appear.
Of course, water is not the only resource that causes cities to appear. Mineral wealth, from coal and limestone to gold and diamonds to petroleum and natural gas, invites prospectors to gather forming communities that grow into cities. Nor are natural resources the only economic inducement. If there is a city at South Bay Harbor and another at North Lake Port, and one at Eastern Inlet and another at West Mountain Mine, there will be roads connecting these places–but the road from Eastern Inlet to West Mountain Mine will cross the road from South Bay Harbor to North Lake Port, and the traffic through there makes it an ideal spot for commerce, and thus if the problems of food and water can be solved easily, a city will form at the crossroads.
As we said, though, not all cities are begun for commercial reasons; some are started for government reasons.
The most obvious of these are forts, from walled cities more ancient than Jerusalem to medieval castles to cavalry troops posted in the American west. Governments decide that they need to defend something–land, resources, people, transportation routes–and build a fortress. People recognize that the existence of the fort means protection from whatever danger is perceived, and so collect near it.
Military forts tend to be extremely well designed for their original purposes; armies tend to be that way about encampments. Thus within the walls of the fortress housing and facilities and accommodations for food, water, ammunition, supplies, vehicles, animals, and anything else deemed necessary to the local military effort, will have been carefully organized. The problem is that foresight is not always perfect. Sometimes the situation at a particular location becomes more contested than anticipated, and troop strength has to be increased, doubling or tripling the population inside the walls. If this continues intermittently for long enough, the fort might be expanded, but the expanded fort will be less efficient than the original simply because it has to be built around what already exists. If it is not expanded, it still will be modified, as facilities intended for storage become barracks for troops, new structures are constructed in open spaces to provide protected storage for the displaced goods, and the original plan is altered in uncounted ways.
The placement of forts is frequently sensitive to geography. High ground is typically advantageous, so mountains and hills are often choice locations. Often they are intended to control movement, such as passage through a mountain pass or at the mouth of a river, and will be placed above or even in the middle of such a bottleneck. Artificial hills and even islands have been built to support such forts. Water is again often a factor, not only because the keep needs a water supply but because rivers and lakes form natural moats which help protect that side of the fort.
Of course, outside the walls the only control the military has over the rising city is the ability to insist that nothing be built within a certain distance of the walls–after all, when the hordes come, whether orcs or Huns or Vikings or Apaches, they will readily use any such structures for cover, so the army will not permit them too close. Thus other than that clear space, the town will grow haphazardly into a city, unless some government takes control of it.
Military uses are not the only governmental purpose that will create a city. Sometimes they are created for administrative purposes. Washington in the District of Columbia is such a city, built to a plan because the nation needed a centrally located seat of government to oversee law and taxes for the thirteen states that was not itself part of one of those states. The oldest sections of Philadelphia were designed by its founder, a man granted a huge amount of land to establish a colony who had the foresight to recognize that this riverport was going to be a major hub in the development of the surrounding land. It is thought by some that Emperor Nero set fire to the poor section of Rome (and blamed the Christians) so that he could take the helm in what may have been the world’s first urban redevelopment plan. Such planned cities appear in places where the governments think them convenient for the purpose–centrally located in the geographical area, or on land with the potential to become a major economic center, or in sparsely populated areas where the government wants to encourage some kind of development, whether agriculture, industry, or tourism.
So these are the major reasons why cities appear where they do, and when you’re designing your world maps you should think about what cities are where and why. That will then give you the points you need to connect with your country roads, and frame your map.