A woman tends her small shop on the street in Hanoi. Many shops are part of “shop houses” where shop owners live in the relatively affordable residences above.
“Lowly, unpurposeful, and random as they may appear, sidewalk contacts are the small change from which a city’s wealth of public life may grow.”
— Jane Jacobs, The Death and Life of Great American Cities
It is a remarkable phenomenon, bordering on miraculous, that a city like, say, 19th Century New York, can take penniless immigrants from Ireland or Italy or Poland, and in the space of a few decades, turn them (or their children) into shopkeepers and factory owners and lawyers and senators — and poets and artists and professors. This is what ultimately draws people to cities: not simply to secure “jobs” but to develop as human beings, which is to say, to improve health and well-being, to increase opportunities for women and (often smaller) families, and to expand the creative capacities and the wealth of human culture.
This is not a random process. Education is surely a part of it, but so is the expansion of opportunity within physical networks of potential collaboration. This human development can happen because there is something in the network of connections within cities that allows these opportunities to occur, manifested within real physical space occupied by real people. That physical space includes, at its most fundamental level, the public space of the city: its streets, squares, parks and plazas, where friends, strangers and (importantly) near-strangers can encounter one another.
Jacobs’ observations about how successful cities actually worked led her inevitably into the subject of urban economics. How do people create new knowledge, and new work? What is it about cities that makes this possible? Her answer was that people develop and exchange knowledge with one another within cities — not only with people they know well, in their own industries, but with other people they know less well, in other businesses or other entire industries. The subject of her work in this field came to be known as a “knowledge spillover,” and her particular observation is now known in economics as a “Jacobs spillover.”
It was this, she found, that lay at the heart of the capacity that cities have to support the growth of knowledge exchanges and combinations, producing innovation and economic growth. This is how a city like 19th Century Detroit, for example, could become a new hub of economic expansion in the early 20th, in the entirely new and unheard-of field of automobile manufacturing.
In her book The Economy of Cities (1969), Jacobs noted that Detroit had two things going for it. One, the city was already a center of a diverse network of businesses related to of shipbuilding, which meant there was a great diversity of enterprises that would serve the new automobile industry well — makers of motors, wheels, pulleys, carriages and the like. Two, just as important, the city had a network of spatial connections between all these individuals and enterprises, not only within the existing companies, but outside of them. Workers could meet up and form new connections within a broad range of urban spaces, both private and public. This “mixing network” provided fertile conditions for the growth of new enterprises, and even a new industry — which is precisely what happened in due course.
Earlier, in The Death and Life of Great American Cities, Jacobs had spent a lot of time talking about “lowly” sidewalks, and their importance for creating safety, assimilating children, and providing the essential contacts on which the life of the city is built. It was not that sidewalks were the only place for making such contacts, but that sidewalks form an essential strand of what Robert Putnam has referred to as “multi-stranded” social connections.
This understanding of diverse networks, built on human-scaled public spaces including sidewalks and their edges, is the foundation on which her economic work was built. At heart, hers became an economic vision of the city — an understanding of the “organized complexity” of human activities and creations of wealth that the city makes possible. As we now understand from network science, this system gets its power not from a “command and control” approach from the top, but from a broadly interconnected, partly self-organizing network.
In essence, she argued, most of the economic benefits for the city are not generated by any kind of concentrated power center, but are actually the result of a broad form of socio-economic interaction all across the city network, involving many small and mid-sized businesses and as well as start-ups. (And yes, a few big businesses too — though if they become too dominant the city can stagnate.) The many small-scale innovations within this mixing network compound to generate the wealth of the city, in part by replacing imports and eventually creating new exports, and in part by making possible creative synergies that are often unexpected.
It is this capacity that offers opportunity for many different people at many different scales — and not only at the top, in the form of either big companies or big government programs. (These large extremes dominate the attention of today’s most prominent “right” and “left” ideologies, but for Jacobs, both of these ideological fixations miss the deeper point.) This inherent dynamic of cities can, if we put it to work for us, take penniless immigrants (as it did, say, in the example of New York that I gave earlier) and turn them into middle-class shopkeepers and manufacturers and professors and artists — and all the other economically and culturally creative people of the city.
It is true that much of the wealth of a city is temptingly visible at the top — and often in the city core, especially of late — but that does not mean it is wholly or even mostly generated there. But over-concentration of attention at the top, and in the core, not only fuels the wealth gap and the dynamics of gentrification, it distracts from the real engine of urban growth, according to Jacobs. The result is likely to be stagnation, loss of affordability, increasing segregation by income, declining quality of life, and a spiral of urban failure and recrimination. I will have more to say about this problem later in the book.
For Jacobs, however, the real engine of growth is powered by many diverse people interacting within the continuous fabric of physical spaces of the city, including the crucial public realm — the sidewalks and other spaces where people encounter one another, share information, pass along contacts, and create the “knowledge spillovers” that are essential to innovative expansion. Within this continuous fabric, private social spaces are important too, of course, but the “glue” that binds them all together is the critical public realm. Cities are, in effect, “socio-economic reactors” that generate wealth, in the broadest sense of the term (including cultural wealth).
This is a more diffuse and less visible form of wealth production, but it is ultimately a more powerful one. In fact Jacobs argues that this is the real wellspring of human development. Simultaneously, it is a way of increasing resource efficiency (because efficiency is financially rewarded) and reducing ecological impacts. This efficiency-trending dynamic goes a long way to explaining why compact mixed use cities can be, on a per capita basis, so much “greener” than more sprawling places, as my own research and many others’ has shown.
There is another, related implication. Of course it is possible, up to a point, to replace the diversified, continuous public realm of urbanism, and the catalytic growth it produces, with a system of segregated, machine-like capsules: automobiles, isolated offices and campuses, suburban housing monocultures, and the like. It is possible, in other words, to trade away a “natural human-capital city,” for an artificial kind of city that is nonetheless economically productive, at least in the short term. Indeed, we can see many examples in the US and other countries.
But this economic development is only possible with massive injections of resources — notably fossil fuels — at unsustainable rates. We could think of this this model as the “crack cocaine” of urban development: it will certainly produce a very quick and intense high, but one followed by a disastrous (in this case planetary) hangover.
This is the urban crisis that we now face. The world is rapidly urbanizing according to precisely this addictive model. We are on track to produce more urban fabric by area in the first five decades of the 21st Century than we have produced in all of human history. What will be the model, if not this one? How will we avert the catastrophic collapse that seems inevitable under the current unsustainable path? Those in the urban professions will certainly be challenged to respond to this crisis (for example, in implementing the “New Urban Agenda” that has just emerged from the UN conference on housing and sustainable development).
Will we continue to stake our entire future on this economic “crack cocaine high”? Or will we take a more hopeful view, and see the city (and town) as an engine of sustainable regeneration, taking the steps needed to unleash the powerful urban dynamics on offer?
The latter choice will demand of us a more subtle, more catalytic approach to urban growth — one more focused on harnessing and directing the self-organizing capacities of cities, towns, and neighborhoods. It will demand that we avoid pursuing the latest “silver bullet” — the big employer or big sports stadium — and focus on a broader and more diversified form of urban economic development. It demands that we pay more attention to what Jacobs called “the kind of problem a city is” — and it is not the kind that we have too often supposed.