Very occasionally, the opportunity arises for a group of people to decide where and how to build a city. In 1792 the legislators of North Carolina confronted such a moment. It had been decided that a new state capital was going to be built and that that state capital should ideally be far from the sea. Without having to worry about the best beachfront property, the legislators found themselves free to prioritize other things. So it was that they decided upon the rule to be used in placing a capital. It should, they concluded after much contemplation, be no farther than ten miles from Isaac Hunter’s Tavern, their favorite bar.

Isaac Hunter's Tavern exterior, Raleigh, NC, 1969. Photo credit: NC Office of Archives & History via

Isaac Hunter’s Tavern exterior, Raleigh, NC, 1969. Photo credit: NC Office of Archives & History via

So it was that the town of Raleigh, now a city, came to be situated between the mountains and the sea and distant from any navigable river or really any other existing town at the time. The story of Raleigh’s founding begs many questions. One can wonder about just how good the beer was or just how drunk the legislators were, for instance. But perhaps the most interesting is how, more generally, we decide how our cities are born, grow and change.

As humans, we are, of course, not the first animals to make choices about how to build the places that we live. Relative to the size of their bodies, the palaces of many ants, termites, wasps and bees are cities too. Seen from above, or in castes, these cities are not random. They represent, we now know, what happens when “dumb” individual insects carry out simple rules about where and how to build. Many features of termite nests, for example, can be recreated in computer models in which simulated termites just have a small handful of rules about where to put mud, how to stack in, and when to stop. Out of similar rules emerge the hives of honeybees or the magnificent chambers of some ants. What is more, these rules have evolved, under natural selection to be, if not perfect, closer and closer each generation. Better in this case is not necessarily beautiful (though the beauty of many nests is undeniable), but instead functional. The termites, ants and wasps with genes for building better nests have more babies that, in turn, do better themselves.

Insects do not build their cities consciously. Their rules are the subconscious stuff of chemistry, chemistry that favors one act over another. Humans, like the legislators in North Carolina, can decide to do one thing relative to another. As a result, we possess the ability to imagine cities, to imagine, really, every detail of how roads and buildings stretch out across a landscape. This is what happened in the case of Raleigh. Raleigh’s site was consciously chosen and its downtown was consciously planned. If then, we are thinking about the future of cities, we should think about which conscious decisions we should make.

The “problem,” however, is the special mix of money, democracy, and personal choice with which we have imbued America. The problem is that cities are not decided upon and then crafted in the way that they might be in a book on design (or in China), but instead they are the net result of many decisions, some of which are heavily reasoned and lead to functional cities, some of which relate to where bars are, some of which relate to who has the most money, some of which relate to which places are cheap to build, some of which relate to each of a million other bits of human capriciousness. As a result, it has proven very hard to plan the expansion of cities across landscapes.

And so it was in this vein that Adam Terando and a group of collaborators (of which I am one) decided to use a new approach to model the future of cities. Forget plans. Forget ideal scenarios. What they decided to do was to use a model that would, assuming humans were like ants, capture the kinds of rules that humans tend to use to expand cities. Terando, a research scientist at the USGS Southeast Climate Science Center in Raleigh, North Carolina, developed a model that captured with a few rules how the antlike humans in different parts of the Southeast tend to expand their cities. He then tested those rules against the past and, in the same way that a few rules predict the way termites build, he found that these rules were predicting where humans built. But then the more exciting step. Terando projected these rules into the future. He used his rules to predict what would happen in the southeastern United States if urbanization continued to expand according to these rules, subconscious unspoken rules, of growth.

The result is the map you see here. In this map what you see is that the area from Charlotte, North Carolina to Atlanta, Georgia becomes one giant city. Raleigh and Durham, North Carolina are then a separate megacity connected to that much larger one. The panel below makes this more clear. In it you can see the megacity, highlighted.


If this megacity comes to be, what will happen? Well, we know that larger cities EVENTUALLY achieve efficiencies. They are better at using energy (less is used per person). Transportation costs go down. The need for gas stations goes up. Per capita innovation increases (more people = proportionally more great ideas). It also means greater potential for social connections and the flow of information, ideas and opportunities. Many great things come of big cities. But eventually. At first, unless they are planned for, the great big city will be accompanied by great needs of re-imagined infrastructure. Better transportation. Better integrated parks. Better designed spaces. In light of the future megalopolis, CHARLANTA needs to invest in what will be needed for this future.

But the strength of the work of Terando and team is not in this particular prediction (on which one might still reasonably make important planning decisions and investments including where to prioritize conservation). The strength of this work is that it will ultimately allow Terando and others to imagine what the cities of the future will look like if we change the rules by which we allow them to grow. We can see which rules produce the cityscape that best matches our hopes and dreams both in terms of the places we live and the places we leave for the rest of life to inhabit. This is the great hope. It is also, as it turns, what separates us from the ants, bees, termites and wasps, or what might. The ants and other social insects can change their rules via evolution and evolution alone. They change their rules when those with rules that don’t quite work fail, one colony at a time, to spread their genes. The hope is that we as humans can learn before failing, that we can envision the consequences in changes in how our kind spreads one hill to the next, and make good choices, reasoned choices. Whether we actually do will be up to this generation (at least in the context of Charlanta), but at the very least, Terando and team have now provided us one of the tools.

Read the paper: Terando AJ, Costanza J, Belyea C, Dunn RR, McKerrow A, et al. (2014) The Southern Megalopolis: Using the Past to Predict the Future of Urban Sprawl in the Southeast U.S. PLoS ONE 9(7): e102261. doi:10.1371/journal.pone.0102261