When Cities Get Too Big

Many of the things that I talk about relate to the benefits of urbanization, and there certainly are lots of benefits. But is there a point that cities can grow so large that they become unmanageable? Cities can be efficient because they bring together all different types of people with different knowledge and skills, which allows many types of industries to flourish. My guess is that somewhere between 5 and 10 million people, cities actually start to become less efficient for the following reasons.



Diminishing Returns: As the number of people available to fill a certain function increases, each additional person adds less to the value of the function. For example, say that one out of every one million people becomes a dog whisperer. The first one or two dog whisperers in a city may provide great benefit to those who wish to have their dogs trained; however, adding say ten more dog whisperers to a city will not provide much additional benefit because they are not needed. The value of each dog whisperer declines, but the waste that they produce remains constant.

Congestion: One of the great things about cities is that they can pack lots of people into a small area by building up. However, one problem is that no matter how high into the sky buildings stretch, in order to move from one building to another, people must always go to the ground floor and then either walk, take public transportation or drive to their destination. In this layout, a theoretically unlimited number of people can live in apartments and work in their offices without feeling cramped, but nothing can truly reduce the congestion on streets. Eventually even walking short distances becomes difficult. Consider New York City where it is nearly impossible to drive, subways are always packed and it is a struggle to walk a single block without bumping into someone. This can further limit the amount of distance a person will travel and rather than being able to move about the city, a person may feel confined to the few blocks around them because of the frustration and time it takes to go anywhere else. This can actually reduce the value of the services that are too far to reach.

Disasters: The largest cities have the most to lose in cases of disaster, and misfortunate can take many forms be it hurricane, blackout, terrorist attack or snowstorm. Any of these events can cripple an area, but the largest cities have the most to lose. While a blackout in a small town may simply encourage residents to sit in their homes and light candles, I can recall the massive New York City blackout from several years ago. The streets flooded with people and cars and everyone became stuck everywhere. Nobody could move and the city was full of panic. It was a complete mess. Situations like this can strongly interrupt the flow of life in large cities.

I remain a strong advocate of urbanization because I think that in most cases the benefits outweigh the costs. But in the modern era where cities have the resources to expand upwards of 5 to 10 million people, we must create new ways to attack these problems. The way that cities are currently designed, they have limits. In order to push the population limit higher, cities will need to plan some new and creative solutions.