There is a big issue that has not been answered properly by urban planners, architects, engineers, geographers and other people who study cities. The issue is the one related to the city limits. Obviously, it is difficult to define it and more difficult to do it in a few blog posts, but I want to make an approach to some matters that are important in this question in the following three posts.

We are witnessing a huge urbanization and an accelerated process in city growing. But, apart from the urbanization process question, there is a more interesting question for which I do not have an answer, and it is How big can a city be? I have not found a definition of city containing the size component yet.

Despite this I already know that cities somehow are defined by people gathered, so maybe we can have some answers thinking about that matter. Going through this path we can think that people also need some “stuff” for living. Firstly, I am sure that people need to feed themselves, but nowadays food production happens outside the city, so this will not be the key factor to define our cities limit, although it was before the 15th century. Secondly we can think about energy, but we can reach the same formerly conclusion, energy can be produced in a “national” scenario, so it cannot be the defining question. We can also think about a great number of issues and we usually reach the same conclusion, we can think about information, goods, money, etc. and we have to assume that this ´stuff´ can come from out of the city limits.

To solve this problem I started to think more in people´s relations and in the advantage of proximity relations between people and I found one service that has to be given in the city to take advantage of agglomeration, transportation. Transport has to solve the physical problem of communication inside the city and it has to solve the problem in a certain time. It is assumed that a person can´t spend longer than a certain time to go and return to or from his house (one hour/one hour and a half maximum per trip). So with the fastest transport modes that we nowadays have, cars and metropolitan railways, we could imagine a city limit defined by their influential area and by the time that a person can spend in transport in a single day.

I think that this is an interesting point of view, because we can see cities as relational systems more than agglomeration places and this vision allows to link people with the city limit through the physical needs of communication.


  1. Pingback: Definition urbanization | Mandersoninsurance

  2. Use Chicago as the perfect example. Tell us how O’hare Airport is actually part of the City, yet outside the imaginary City limits. Funny how TAX base becomes the dominate factor here. Couldn’t go east, so they expanded the airport West.

  3. Yeah, John, you are right. If you think about serving the chicago population, O´hare airport is based OK, because it is inside the transport radio. When you are inside this radio there are other influences that matters, in this case taxation could be the key point.
    Thanks for writting!

  4. hola José María,

    the city limits is for me one of the most relevants questions about the urban planning

    it’s a joke but it’s a nice example: when I was a child, when playing games like simcity I allways get to the end of the map and allways expected to have bigger maps to expand

    some of the questions we can discuss, under those perspectives:

    – land and resources spoiling
    – good delivery (limiting > gives to 24 hours operating city)
    – conmuting traveltime (limiting > lower class people spends most of the salary in long conmuting trips up to the moment they are no longer interested in jobs downtown > documented in London)
    – self-sufficient neighborhoods, rehabilitation policies (part of the solution?)

    thanks for sharing your thoughts

    Joan Valls

  5. Hola Joan,

    The first and most important thing, I also played simcity when I was younger. This had to be a requirement for working in metropolitan planification!

    The topics that you propose are really interesting and we can talk about them for hours. I´m just saying some ideas about them. About spoiling land, we have to internalize the real costs of it, because nowadays the incentives to spoil land and resources are really high. About delivering goods the answer is similar than before, the real costs of transport are not internalized. When all this cost and others will be internalized (because resource shortage, I guess) an anti-globalization process will happen.

    Refering commuting, as I said, I think that it is the key for understanding this physical city limit, because finally cities has to be inhabited by people that solves their life problems in it. And this is also related with self sufficient neighbourhoods or whatever self sufficient piece of land for living.

    thanks for your comment Joan

  6. Joan Valls

    thanks for your reply José Maria

    just to warn simcity 5 is under develop and maybe some of these ideas would be helpful for them

    thanks once again


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