Wonders of the “urban connectome”


Cities, like brains, are immense networks of connective patterns built up over time. Understanding this evolving structure will help us to formulate better urban policies and practices.

Few developments in the sciences have had the impact of the revolutionary discoveries in genetics, and in particular, what is called the “genome” – the totality of the complex pattern of genetic information that produces the proteins and other structures of life. By getting a clearer picture of the workings of this evolving, generative structure, we gain dramatic new insights on disease processes, on cellular mechanisms, and on the ultimate wonders of life itself. In a similar way, geneticists now speak of the “proteome” – the no less complex structure of proteins and their workings that generate tissues, organs, signaling molecules, and other element of complex living processes.

An important characteristic of both the genome and the proteome is that they work as totalities, with any one part potentially interacting with any other. In that sense, they are immense interactive networks, with the pattern of connections shaping the interactions, and in turn being shaped by them. Proteins produce other proteins; genes switch on other genes. In this way, the structure of our bodies evolves and adapts to new conditions – new infections, new stresses, new environments.

It turns out that something very similar goes on in the brain. We are born with a vastly complex pattern of connections between our neurons, and these go on to change after birth as we experience new environments and learn new skills and concepts. Once again, the totality of the pattern is what matters, and the ways that different parts of the brain get connected (or disconnected) to form new patterns, new ideas and pictures of the world.

Following the naming precedent in genetics, this structure is now being called the neural “connectome” (because it’s a structure that’s similar to “genome”) and the race is on to map this structure and its most important features. (Much of this work is being advanced by the NIH’s Human Connectome Project.)

What do these insights have to do with cities? As Steven Johnson noted in his book Emergence, there is more in common between the two structures than might appear. There is good reason to think that, as with brains, a lot of what happens in cities has more to do with the overall pattern of connections, and less to do with particular elements.

As Jane Jacobs pointed out over half a century ago, the city is a kind of “intricate ballet” of people interacting, going about their plans, and shaping the life of the city, from the smallest scales to the largest. This intricate pattern is complex, but it’s far from random. As Jacobs argued, it exhibits a high degree of order — what she called “organized complexity.”

And it’s physical, starting at the scale of the sidewalk, and encompassing all the other movements and connections of urban activity. “Sidewalk contacts are the small change from which a city’s wealth of public life may grow,” she wrote. We may also be plugged in electronically by telephone and now Internet, but (as research by Robert Putnam and others is showing) the root of the system is the physical proximity with the people we know and work with.

More than that, this pattern of connections generates remarkable efficiencies, forming a kind of “network metabolism.” Jacobs has since become famous for observing highly local “knowledge spillovers,” casual transfers of knowledge about a job or a new tool or idea, that help to grow new enterprises and new economic activities. Her insight, now called a “Jacobs externality” by economists in her honor, helps to explain how a city generates wealth. As we have written before, this phenomenon might well help to explain why cities are so efficient with resources per person, relative to other places.

In the same vein, the brain scientists offer some other important insights. For one thing, more important than the density per se (of neurons, or of people) are the patterns of connections. So we have to be able to ensure that many “neural pathways” can form and re-form – in the case of a person’s brain, that the person is healthy and well-nourished enough to remember, and learn. In the case of cities, we have to ensure that we have well-connected, walkable cities, facilitating many cross-connections.

The brain scientists even believe now that this pattern of neural cross-connection is key to the formation of consciousness. In effect, the different parts of the brain join up into a larger system, and the result is that the system self-organizes into a state that is smarter and more aware. When a brain sleeps, this larger pattern seems to dissolve into fleeting sub-patterns – and we experience the loss of consciousness, and sometimes, dreaming.

Something similar might be going on with well-connected cities: they can self-organize to become “smarter” in their ability to generate great urban vitality with fewer resources. But this is true only if their “neurons” (the people) are able to be connected, especially physically connected, in this way.

Similarly, a city can “lose consciousness” by becoming too fragmented and too sprawling. Automobiles and other machinery can help to connect the parts of the city, but only in a very limited and encapsulated way. By contrast, a walkable public realm has vastly more capacity to form and re-form connections between people, allowing a dynamic pattern of interaction to form and sustain across the city’s urban fabric.

This lesson of self-organization carries an important implication for planners and urban designers. It suggests we need to focus less on the specific elements in relation to one another – and how we might imagine they are best placed – and focus more on how we can help them to self-organize into more complex (and more efficient) patterns.

On the other hand, human brains do not start from scratch as we once thought, nor do societies – we all have patterns that we learn and apply to new situations. So too, cities have patterns that facilitate this network structure. Like a good memory or innate knowledge, the best walkable cities of history offer us many good reusable patterns to create vibrant, walkable, resource-efficient cities.

A corollary is that in our automobile-connected suburbs, it seems we have been replicating this pattern of connections – but only with heavy and unsustainable inputs of resources. Furthermore, as noted before, the structure of encapsulated cars, and existing networks of people we already know, are no match for the open-ended nature of public space networks, and their capacity to exploit “propinquity and serendipity” – the accidental connections with people we don’t already know, where, as research shows, the new knowledge and innovations form. If we want more resource-efficient cities – and more creative and resilient economies – then it seems we will have to look much harder at this dynamic, and ways to exploit it to our advantage.

How can we do this, concretely? The brain scientists are working hard to map the connective patterns of particular brains, to get some idea of how the patterns tend to form characteristically within the “human connectome.” For cities, it seems we might do something equally useful: map the characteristic urban patterns that have proven most conducive to this connected vitality, and that also do not interfere with – or better yet that promote – the capacity for urban self-organization.

In a sense, we already do this when we speak of design types, or planning models. But this work is usually very constrained by parochial debates within the architecture and urban design disciplines over “progressivism” versus “historicism.” The result is that there has been a stagnation of real progress in this area. At worst, we have slipped into what Jacobs called a “neurosis” of “imitating empiric failure, and ignoring empiric success.”

By contrast, the brain scientists point to another, less ideologically constrained path. It seems we might have much to learn from a more open, aggressive mapping and re-applying the genetic patterns of such an “urban connectome,” looking at the most effective patterns from a range of cities around the world – and over centuries of evolution.

LSE researchers: beware of the “build baby build” approach


“Upzoning is far from the progressive policy tool it has been sold to be. It mainly leads to building high-end housing in desirable locations.”

As this blog has long argued, the challenges of affordability, equity and sustainability are complex, and require a comprehensive approach, including economic tools, “polycentric” regional planning, and other strategic interventions.  These challenges are not likely to be addressed with simplistic “silver bullets.”  Case in point: the idea that just building more supply (especially in the cores) will automatically result in lower prices, more opportunities for formerly excluded populations, or more sustainable urban types.  (What some have called a “build baby build” approach.)

In recent research discussed on the CityLab blog, economic geographers Andrés Rodríguez-Pose and Michael Storper of the London School of Economics found that “Upzoning expensive cities is no match for the deep divides within—and especially between—cities, and is wholly insufficient to remedy them.”

The research by LSE is hardly the first to point out this problem with “build baby build”.  As the CityLab article points out, “Economist Tyler Cowen agrees that the ultimate beneficiaries from zoning and building deregulation are landlords and developers. As he puts it, “the gains from removing taxes/restrictions on building largely will be captured by landowners … More stuff will be built, urban output will expand, land still will be the scarce factor, and by the end of the process rents still will be high.”And a recent study by Yonah Freemark found that upzoning in Chicago led to higher, not lower, housing prices, while having no discernible impact on local housing supply.”

The author of the CityLab article, Richard Florida, expressed dismay at the barrage of derogatory criticism that he and the LSE economists received from defenders of the “build baby build” approach.  “That makes little sense,” said Florida. “The paper is an important cautionary tale. The authors are not saying that we should not build more housing. They are simply saying that doing so won’t magically solve economic and spatial inequality, because both are deeply rooted in the very nature of the geographically clustered and concentrated knowledge economy.”

But perhaps the effects of financial and other self-interests are far more seductive than the calm and reasoned approaches that are called for.  Perhaps the lesson here is the one famously offered by Upton Sinclair: “It is difficult to get a man to understand something, when his salary depends upon his not understanding it.”

Excerpts from the CityLab article are below, and the entire article can be read here.

new paper by two leading economic geographers suggests this argument is simply too good to be true. Titled “Housing, Urban Growth and Inequalities” and forthcoming in the journal Urban Studies, it’s written by Andrés Rodríguez-Pose of the London School of Economics (LSE) and Michael Storper, who divides his time among the LSE, UCLA, and Sciences Po in Paris. According to Storper and Rodríguez-Pose, the notion that an insufficient supply of housing is a main cause of urban economic problems is based on a number of faulty premises. They say the effect of supply has been blown far out of proportion.

They agree that housing is part of the problem: “Housing market failures can imperil local economic growth and generate problems such as segregation, long commute times, deteriorating quality of life, homelessness, and barriers to social mobility for certain populations,” they write. But housing policy, and zoning restrictions in particular, are certainly not the be-all and end-all of urban problems. Upzoning expensive cities is no match for the deep divides within—and especially between—cities, and is wholly insufficient to remedy them.

“Housing is an area where the law of unintended consequences is most powerful,” Storper recently told Planning Report. “The idea that upzoning will cause housing affordability to trickle down within our metropolis, while also setting up Los Angeles and San Francisco as the new golden land for people in less prosperous regions, is just a lot to promise—and it’s based on a narrative of housing as opportunity that is deeply flawed.” And as Rodríguez-Pose told me via email: “Upzoning is far from the progressive policy tool it has been sold to be. It mainly leads to building high-end housing in desirable locations.”

Rodríguez-Pose and Storper question several pieces of evidence that stand at the heart of this market-urbanist view, a perspective they dub “housing as opportunity.” Whereas some urban economists suggest a close relationship between housing supply and prices (with places that add supply having lower prices), Rodríguez-Pose and Storper find the relationship to be weak.

Likewise, some market urbanists point to an association between city population size and/or density and economic growth. But Rodríguez-Pose and Storper argue that this too falls away under close scrutiny—the link between city population in 2000 and subsequent economic growth from 2000 to 2016 is weak to “non-existent,” on their analysis.For Storper and Rodríguez-Pose, the rising spatial inequality between cities and metro areas stems from different kinds of economies that distinguish different kinds of cities, not from differences in housing costs. Or as they put it, “the basic motors of all these features of the economy are the current geography of employment, wages and skills.”  

The economies and talent bases of cities have diverged over time. Expensive cities have much larger clusters of leading-edge tech and knowledge industries and of highly educated, skilled talent. It’s this, rather than differences in housing prices, that is behind growing spatial inequality.

“The affordability crisis within major urban areas is real,” they write, “but it is due less to over-regulation of housing markets than to the underlying wage and income inequalities, and a sharp increase in the value of central locations within metro areas, as employment and amenities concentrate in these places.”

A key factor here is the growing divide between highly-paid techies and knowledge workers and much lower-paid people who work in routine service jobs. These service workers end up getting the short end of the stick, spending much more of their income on housing in expensive cities. “Under these circumstances moving to big cities provides no immediate benefits for workers without college education,” Rodríguez-Pose and Storper write.

Upzoning does little to change this fundamental imbalance. Because land in superstar cities and tech hubs is so expensive to begin with, upzoning tends to create even more expensive condominium towers. “While building more affordable housing in core agglomerations would accommodate more people,” the authors note, “the collapse of the urban wage premium for less-educated workers means that the extra housing would mostly attract additional skilled workers.”

Opportunities for improved wages in core areas have stagnated, and the “ladder has shrunk.” Therefore, the decline in interregional migration can be attributed to many factors, including the new geography of skills and wages. But housing restrictions in prosperous areas wouldn’t top the list. And upzoning ends up fueling, not relieving, economic and spatial inequality. As Rodríguez-Pose told me: “Income inequality is greater within our cities than across our regions. Upzoning will only exacerbate this.”

“Planning deregulation and housing costs are neither going to solve the problem of areas lagging behind, nor are they likely to have an impact on the economic development of dynamic cities,” Rodríguez-Pose and Storper write. Worse, they caution, “an excessive focus on these issues at the expense of serious and sustainable development strategies, can fuel economic, social and political distress and anger in declining and lagging areas that can threaten the very foundations on which economic activity, both in less developed and more prosperous areas, has been erected in recent decades.”


This last point deserves attention.  By focusing on a kind of “voodoo urbanism” approach — by concentrating too much on the urban cores, including new building there, and hoping the benefits will “trickle down” to everyone else — we are not only not improving the affordability and equity issues, we are actually fueling a spiraling dynamic of “left-behind places.” These  include the suburbs, and also, importantly, the smaller towns and rural areas where much of the so-called “populist revolt” is occurring (in both the US and other countries).  Rodríguez-Pose in particular has argued for a more evenly distributed, “polycentric” approach to economic and human development, within city regions as well as national regions. 
 To us this suggests a more even-tempered and polycentric approach to development across urban and national regions —  creating a network of walkable, compact, transit-served places at a range of scales, densities, and (importantly) costs.  As we have written before, this approach might be thought of as a kind of “Goldilocks urbanism”.  Yes, cities do generate economic and cultural benefits from concentrations of talent, but also from “spreading it around.” Getting the balance “just right” (neither too hot nor too cold) is not just about fairness; it turns out to be better for everyone’s bottom line too.  

Why “cities of opportunity” need well-connected public space systems

A night market in Hong Kong, providing opportunities for economic transactions and social mixing along a busy street.

“Cities of opportunity” – the theme of the 2020 World Urban Forum – reminds us how cities facilitate connections between diverse people and resources. thereby generating opportunities for all to develop and prosper, in economic, health and cultural dimensions. Public spaces are emerging as the essential platform on which these connections between people and resources develop. New research shows that public spaces are supplemented by, but not replaced by, other more private forms of contact, which tend to reinforce already existing connections. By contrast, public spaces play a role in “propinquity and serendipity” which are emerging as key drivers of innovation and opportunity. Cities for all, by definition, must offer public space (including streets and other spaces) for all. An important research question is, then, what is the role of public space in fostering innovation, creativity, and opportunity for all? What is its role in promoting resilience and climate adaptation?  And what tools and strategies can we use to achieve these goals?

The New Urban Agenda contains nine paragraphs describing the importance of public spaces. Among the benefits identified are social interaction and inclusion, human health and well-being, economic exchange, cultural expression, improving resilience of cities to disasters and climate change, physical and mental health, household and ambient air quality, reducing noise, promoting attractive and livable cities [and] human settlements, and prioritizing the conservation of endemic species.

These goals are all the more important in an age of rapid urbanization, growing climate stresses, surging informal settlements, threats to the well-being of vulnerable populations including migrants, growing urban inequality in many cities, and increasing trends of urban sprawl and fragmentation, resulting in the degradation or loss of public space. Yet it is public space that is most helpful in responding to these challenges, as the New Urban Agenda makes clear.

The adoption of the New Urban Agenda by acclamation by all 193 member countries of the United Nations stands as a landmark achievement in urban history. However, that achievement must now be followed up by implementation – by the sharing of tools and knowledge about how to develop, protect and improve public spaces, and public space networks. Much progress has been made, but further progress depends on further sharing of knowledge and tools.

The Future of Places and its allies will be attending the World Urban Forum, and hope to see many friends and collaborators there.

Report from Side Event at the UN-Habitat Assembly, Nairobi, 30 May 2019

The side event under way at UN-Habitat Assembly, 30 May 2019

“Innovation Districts for Rapidly Urbanising Cities: Opportunities and Challenges” with Ax:son Johnson Foundation, UN-Habitat, and other partners

Report by Dr. Katherine Kline, Co-chair, General Assembly of Partners, Older Persons Partner Constituent Group

Summary:   In recent years, ‘innovation districts’ – neighbourhoods where companies and academic institutions cluster with startups and incubators to produce new products and services – have emerged in cities across the world. In recent research, the success of these innovation districts is linked to mixed-use, compact and integrated urban forms that provide high-quality and inclusive public spaces, catalyzing social interaction and economic “spillover” effects. Removing physical barriers such as walls, fences and roads create networks of public spaces that promote greater diversity of interaction and greater creativity. When innovation districts are anchored in the existing cities, additional dynamics ensue, as they are often linked to urban regeneration processes.

Some of the best-known examples of successful innovation districts are in slower-growing cities of the Global North, including Barcelona, Berlin, London, Montreal, Stockholm, Seoul, and Boston. But many other rapidly urbanizing cities are also employing innovation districts, including Medellin, Wuhan and Johannesburg. What are the lessons for the Global South, and especially for rapidly urbanizing cities? How can innovation districts be planned, and how can networks of public spaces contribute (as called for in the New Urban Agenda and Sustainable Development Goals)? What are the opportunities and also the dangers? This session brought in research evidence and perspectives from planners and implementers from different parts of the world.

Introduction by Michael Mehaffy, moderator: We now have the New Urban Agenda agreed to by all 193 countries, and the focus now must be on implementation.  The NUA and Sustainable Development Goals both contain language about the importance of public space and economic development. There is a new understanding of what cities do to create synergies and “knowledge spillovers,” especially through public space. We see the critical importance of street network connectivity for knowledge spillovers and other creative social and economic interactions. We need a “Goldilocks zone” – a maximum level of diversity, combining the widest possible range of low income and high income — not a concentration of either (i.e. “slum” or “gentrified enclave”). Research shows that over-concentration on either is destructive, economically and socially.

The Metropolitan Policy Program at Brookings Institution has compiled a report on so-called “innovation districts,” meant to take advantage of this kind of interaction in urban and public space. This is an emerging trend globally, tapping into not only “agglomeration benefits” of cities, but the propinquity and serendipity of interactions within public spaces as well as adjoining private ones. “Urban knowledge parks” provide physical assets in the public realm that help to create interactions, especially with “weak ties” (people from different fields with different knowledge). This might require removing fences and walls and adding pathways, they say — sometimes restructuring public space, e.g. in isolated suburban locations. The results knit the district together and strengthen connectivity within the broader metro area, so that these districts do not  become islands with themselves. Truly “smart cities” (a dangerously vague and feel-good term) requires an evolution of our thinking about cities, and the way we plan and design them, especially around public space networks and their adjoining private edges.

Challenges to consider:

  • What are the pitfalls of innovation districts, and “smart cities” more generally?
  • How can these districts be better integrated into their regional urban systems?
  • How can innovation districts avoid over-concentration on one type of innovation, and at the same time, avoid becoming too diffuse?
  • How can the interests of private entities be balanced with public interests?
  • How can innovation districts serve to regenerate the weakest parts of the city, without causing excessive gentrification?
  • What are the tools that we can identify, and how can we share them?

Laura Petrella, Leader of City Planning, Extension and Design Unit, UN-Habitat: We are currently dealing with cities at city-wide scales.  We work from the perspective of the New Urban Agenda:


  • Protection and promotion of human rights and the rule of law
  • Equitable urban development and inclusive growth
  • Empowering civil society, expanding democratic participation and reinforcing collaboration
  • Innovation production – new ideas, economic development

One of the tools is to create innovation districts in cities. They have a contribution to a sustainable transition in an urban environment; they contain a variety of actors; they span the boundaries of academia and industry; they can help transform urban areas into iconic models of urban quality.

The UN-Habitat Strategic Plan is new. The innovation tool is a component to spatial equality, shared prosperity, and a response to climate change. We are interested how these innovation districts connect with the rest of the city:

  • Urban sprawl vs. compactness
  • Segregation vs. Integration
  • Congested vs. Connected

There is now a huge effort underway globally to create innovative new cities, and to attract a wide range of stakeholders from international to local levels. There is strong collaboration with academia in this effort.

Planned city extensions must piggybacking on existing cities – promote business and extended research activities.

Regeneration is also important, the repurposing of existing fabric to revitalize the local economy.

We need city-wide strategies well-distributed across cities.  We need to thereby promote a green economy, combining regulations and incentives (a good example is the current work of Sao Paolo, Brazil).


  • Adequate space for streets and public spaces in an efficient street network
  • Mix of land uses
  • Social mix and diversity
  • Adequate density
  • Connectivity

Jie Song, Deputy Director of Wuhan Land Use and Urban Spatial Planning Research Center: She is an urban planner involved in over 100 projects. In December 2018 they helped to organise “International Placemaking Week”  in Wuhan, with UN-Habitat support. They then founded the China Placemaking Network to share experiences and knowledge. This is now a UN-Habitat innovations project. Wuhan is the largest city in central China with a population of 11 million, and has a famous historic part of the city. In 2018 they organized the International Urban Design Student Competition, a global competition for innovative urban development. They used the case study of Guibei to explore how to make improvements. They renewed historical heritage sites and public spaces, and introduced vibrant mixed-use space.

She showed a project on Deshengqiao Street, a pilot project to engage young people in local planning by using via Minecraft (with Microsoft as a partner). The workshop included 32 people aged 7-77.

Stefanie Chetty, Director of Urban Policy Development and Management at the National Department of Cooperative Governance. South Africa: They look forward to sharing their many experiences how to align with the New Urban Agenda and Sustainable Development Goals. They developed integrated implementation or localizing framework of implementing the NUA with SDGs.

They had four strategic goals:

  • Inclusion and Access
  • Inclusive growth
  • Effective governance
  • Addressing social and spatial inequalities.

They have a huge backlog of untransformed spaces from the apartheid era. South Africa is working to address past issues under apartheid, but this is a huge challenge. Pressures on income are determined by race; although there is a good growth rate, there is still high unemployment; people want to be involved; they want to live where there are basic services. They try to bring in linkages. There are many problems with connectivity, e.g. gated communities. Civil society plays a big role on overcoming these challenges. The informal sector has a role to play too, and it is essential to involve everyone. We must all ask, who shapes our cities and how? With established formal and informal cities, they are trying to integrate cities and create rural urban linkages.

All of this work must consider, what is the state of implementation of the New Urban Agenda?

They recently had a conference with all sectors via the South African Cities Network. They are exploring different ideas, looking at two intermediate cities, working with business and civil society for all, developing inclusive good governance. This work shows we can introduce new ideas through spatial integration.

Ismail Bin Ibrahim, Chief Executive of the Iskander Regional Development Authority in Malaysia: Iskander is an economic region established 10 years ago to support the nation’s vision toward becoming a developed country. They are located on southern tip of Malaysia just north of Singapore. They established 3 phases of growth: development; strengthening growth; and sustaining growth and innovation. Innovation cannot be imposed but must come naturally, and be supported under the right conditions. We need to create an urban ecosystem to support those coming up with new ideas. They embraced an appropriate Comprehensive Development Plan – addressing environment, economy and one more. In Medina City, they addressed strategies of use and development of land from city planners, for example producing a district cooling system. In the city center, government is leading the way, working with small entrepreneurs who turn existing buildings to restaurants for younger people, for example. Growth is now at 8+%, with one problem of a resulting encroachment on agricultural areas. It was important to provide new ways of life for existing residents so that they could remain in their communities while embarking on new types of jobs and work. As one strategy, they supported startups via government grants. Improvements came through major significant projects benefitting the community as a whole.

Lessons learned:

  • Innovation must be long-lasting, giving maximum benefit
  • Inclusive benefit must be for all, not to a single person or group
  • It must be able to be copied by others
  • It cannot be too costly
  • We must create an ecosystem to help people to be creative and innovative

Emmanuel Kombe Nzai, CEO of Jumuiya ya Kaunti za Pwani (Coastal Economic Bloc, Kenya): They are promoting a regional economic effort in the coastal region of Kenya. This is a new project with the European Union along with UN-Habitat. They have many blue (ocean, water) opportunities. They have been setting up policies as an economic development agency, and coordinating with partners. They also have three universities spread across three cities, an important asset. The problem is the vicious cycle of poverty, marginalization, corruption, weak political leadership, feeding one another in a cycle. The innovative solution they are implementing is to change the story focused on Small and Medium Enterprise (SME) incubation. This work is aligned with the 2030 national vision, and includes the Jumiya Investment Fund. They have 6 governors as managers, and they serve as the Secretariat. They are looking to partner to build up the new innovation labs. A catalyst is the Kenya Constitution 2010. So far, there are 7 economic blocs of which they are one. The country has had a failed trickle down policy with little reaching the bottom level. In the new model, they have 14 cross cutting sectors with agriculture, livestock and cooperatives at the top.

During the discussion, attendees asked for additional information about examples discussed and lessons learned. A representative of the GAP and World Blind Union asked Stefanie Chetty about South African examples of inclusion, and wondered how persons with disabilities are included. Do they have indicators of inclusion, and is universal design used? Stefanie reported that they focus on infrastructure we haven’t gotten down to the disability focus. They work with the Secretariat of Police to develop safer and more inclusive cities, and have incorporated many of their policies and strategies.

Speakers at the Side Event.

In praise of “Goldilocks urbanism”

Cities generate benefits from concentrations of talent, but also from “spreading it around.” Getting the balance “just right” (neither too hot nor too cold) is not just about fairness; it turns out to be better for everyone’s bottom line too.

jacobs curve
The goal of urban planning and policy, as Jane Jacobs pointed out, is to maintain an optimum of diversity, in incomes as well as other kinds—neither too many poor in one area, nor too many rich. Drawing by the author.


In recent years, we at the Future of Places have celebrated the power of urbanism: the capacity of cities and towns to create economic dynamism, expanded life choices, opportunities for active living, and healthier, more resource-efficient lifestyles. This power is perhaps most obvious in the dense cores of cities, where people interact with each over across a wide spectrum of private and public spaces that are all connected to that ultimate public space system, the street.

In that celebration we have joined people like Edward Glaeser (author of Triumph of the City) and Richard Florida (author of The Creative Class). In their own works they have described cities as powerful engines of creative social and economic development. They and others acknowledge a debt to the urbanist Jane Jacobs, who championed the humble sidewalk as an arena of human interaction, occasionally producing exchanges of information and “knowledge spillovers” that are surprisingly important for economic as well as social development. “Lowly, unpurposeful and random as they may appear,” said Jacobs, “sidewalk contacts are the small change from which a city’s wealth of public life may grow.” We are learning that other kinds of wealth also grow from the network of seemingly-modest interactions in the city’s public spaces.

But along the way to this very necessary “re-urbanism,” it seems that things have gotten terribly out of balance. The story is distressingly similar in many cities around the world. Newly popular city cores are drawing more people, pushing up prices, and driving out small businesses and lower-income residents. City leaders, alarmed at the trends, try to build their way out of the problems, on the theory that more supply will better match demand, and result in lower rents and home prices. But the efforts don’t seem to work— and even seem to exacerbate the problems.

That’s because cities aren’t simple machines, in which we can plug in one thing (say, a higher quantity of housing units) and automatically get out something else (say, lower housing costs). We can’t just “build, baby build” and solve our problems of affordability. Instead, cities are “dynamical systems,” prone to unintended consequences and unexpected feedback effects. By building more units, we might create “induced demand,” meaning that more people are attracted to move to our city from other places – and housing prices don’t go down, they go up.

Unfortunately, we have been treating cities too much like machines, but for an understandable reason. In an industrial age, that has been a profitable approach for many at the top, and over the last half century, it seemed to fuel the middle class too. More recently, we have begun to see very destructive results—creating lopsided cities of winners and losers, and large areas of urban (and rural) decline. Even government programs meant to address the problems have seemed at times like a game of “whack-a-mole”—say, building some social housing in one place, and seeing more affordability problems pop up in another.

In the years after World War II, and especially in the United States, the largest areas of decline were often in the inner cities, leaving the “losers” of the economy behind, while the “winners” (often wealthier whites) fled to the suburbs. But more recently it has been the cores of large cities that have become newly prosperous, attracting the winners of the “knowledge economy”— and displacing the former long-time residents.

Meanwhile, the inner-tier suburban belts and the smaller cities and towns have suffered marked decline, resulting in predictable political backlashes, including the “populist revolt” of the so-called “white working class.” In the larger cities, lower-income and minority populations have been relegated to more peripheral suburban locations, with limited opportunities for economic (and human) development. This gap in opportunity means a gap in the lower-end “rungs of the ladder” that are so essential for immigrants and others to advance.

Like its Postwar counterpart of suburban growth, this more recent pattern of core gentrification and geographic inequality has also been an unintended result of conscious policies. This time we aimed to achieve not suburban expansion, but the urban benefits of knowledge-economy cities, and their capacities as creative engines of economic development. That is indeed a powerful force to harness. Clearly, however, we failed to recognize the need to temper this growth, and maintain a just balance of opportunity.

Florida and Glaeser, to their credit, have both acknowledged some deep problems with their models. In a 2016 interview, Florida confessed, “I got wrong that the creative class could magically restore our cities … I could not have anticipated among all this urban growth and revival there was a dark side to the urban creative revolution, a very deep dark side.” Glaeser also admitted, in a panel discussion with Florida in 2017, that recent years had seen a blowback from this re-urbanization, in the increasing segregation of winners and losers, and the political fallout that has resulted: “Let me agree that we are facing something of a crisis.”

Too much of a good thing?

The problem with the simple formula of densifying urban cores by concentrating the “creative class” can best be understood from the point of view of network theory, and especially, the theory of how people form economic networks in an urban setting. It’s possible to have too much of a good thing—to over-concentrate, and to rely too much on what are known in the theory as “rich club networks.” These are nodes of concentrated connection that are particularly well-connected, and that therefore offer access to concentrated resources—in this case, concentrations of talent and wealth. Just as in everyday life there is a great benefit to “who you know” and being on the inside of exclusive insider networks of knowledge, wealth and opportunity, “rich club networks” capitalize on similar concentrations of access within them. The trouble is, the benefits may not spill over to other areas outside of those networks.

As Luis Bettencourt of the University of Chicago points out, this network inequality can put a drag on the overall urban system, economically and socially. This is not only because of the costs in areas that are excluded, from problems like crime, policing, incarceration, social services and so on. It’s also a more basic effect of the dynamics of social networks, in what is known as “Metcalfe’s Law.” Networks—in cities or in other structures—benefit from the number of overall interconnected nodes, not just the advantages conferred by elite sub-clusters.

As Bettencourt put it, “the view of cities in terms of social networks emphasizes the primary role of expanding connectivity per person and of social inclusion in order for cities to realize their full socioeconomic potential. In fact, cities that for a variety of reasons (violence, segregation, lack of adequate transportation) remain only incipiently connected will typically underperform economically compared to better mixing cities,” he said. “What these results emphasize is the need for social integration in huge metropolitan areas over their largest scales, not only at the local level, such as neighborhoods.”

Put differently, urban equity and environmental justice are not just about fairness—they’re good for everyone’s bottom line.

But the idea that we should concentrate at the top of the pyramid has its counterpart in supply-side economic theory, which holds that if you promote the interests of those at the top who are creating supply (by giving them tax incentives and other forms of stimulus) they will generate wealth that will “trickle down” to everyone else. George Bush Sr. famously criticized this idea as “voodoo economics”—and yet it became a dominant force in the world’s economic development after 1980, including urban development. We can see now from network theory what the problem is. It is not that the network phenomenon isn’t real, but that it can get out of control. Cities do generate powerful benefits from concentrations of talent—but also from “spreading it around,” and we need to strike a balance between the two approaches.

Perhaps the trouble with Glaeser’s triumphant city cores, and Florida’s creative class, was that they were too exclusive, too dependent on an isolated population of elite knowledge workers, and a limited secondary population that would mainly service their needs. We needed more than densification of cores with walkable, well-connected street grids and mixed use—as beneficial as those are; we needed a more “polycentric,” well-connected and diverse kind of city, geographically speaking too.

In many cities today, it seems, we are seeing the consequences of this “voodoo urbanism” play out. It was thought that if we just take care of the creative class, the universities, the technology industries and their knowledge workforces, then the output of all that urban critical mass, like some kind of economic nuclear reactor, will generate immense wealth that will trickle down to all. This idea is so pervasively seductive that it has been embraced by those who might otherwise resist supply-side economic theory (like the officials in my own home town of Portland, Oregon).

But once again we can turn to Jacobs for an early and prescient warning about the dangers of this approach. She warned against “money floods” which were no less destructive of good-quality and equitable urban development than “money droughts.” More fundamentally, she warned against “the self-destruction of diversity,” in any neighborhood that allows itself to tip over into monocultures of any kind—including monocultures of creatives, or Ph.D.s, or any other sort. Diversity of all kinds is an asset to be maintained, with careful tools and strategies—not only as a matter of social justice, but one of economic vitality too. Again, this is good for everyone’s bottom line.

This was Jacobs’ central argument: that the core task of city planning was to ensure the “generators of diversity:” of people and their numbers, of uses and activities, of pathways, of building ages and conditions—and of geographic locations. Instead of over-concentrating in the core, she suggested, we need a “polycentric” city, with lots of affordable pockets full of old as well as new buildings, and multiple opportunities waiting to be targeted. In such a region, economic growth—and likewise the demand for housing—can be tempered and modulated to remain more even and equitable. We do have tools available to do that: funding incentives, catalytic tools, taxes to dampen speculation, and many others.

At the same time, it seems more important than ever to provide good urban fabric in the suburbs too, where increasing percentages of the population live (including increasing numbers of the displaced poor). “Good urban fabric” means walkable, mixed, transit-served, with expanding opportunities in older as well as newer buildings. It means the same kind of geographic as well as other kinds of diversity, achieved through conscious strategic actions to dampen, incentivize, catalyze, and use other kinds of tools.

In place of voodoo urbanism, we might call this “Goldilocks urbanism”—curating an urban growth that is not too hot and not too cold, nor not too concentrated in any one place. The former approach has done an effective job of destroying historic fabric, raising prices, fueling gentrification, and leaving our cities less sustainable and less equitable. It has also done an effective job making some people very wealthy in a short period. But we continue to follow their simplistic formulas at our cities’ peril.

This post also ran on the CNU Public Square web journal.  Our thanks to them.