Eugenie Birch Explains Why Today’s Slums Are Different, and How to Do Density Right

University of Pennsylvania Professor Eugenie Birch provides a historical perspective on slums, urbanization and density. Photo by Adam Cohn/Flickr

Dr. Eugenie Birch, eminent urban planner and author, is the Co-Director of the Penn Institute for Urban Research and Lawrence C. Nussdorf Professor of Urban Research at the University of Pennsylvania. A long member of city planning organizations and academia, Dr. Birch has worked both in the U.S. and abroad, specializing in urban revitalization, slums and planning history. Sharing her experience on urbanization, informal settlements and gender, Dr. Birch sat down with TheCityFix for an interview.


By 2050, two-thirds of the world’s population will live in urban areas. What are the primary causes of widespread urbanization?

Widespread urbanization has many sources in different regions of the world. We usually characterize them as push-pull conditions. In some instances, rural people are pushed off the land because they cannot earn their living: maybe there is a drought or some kind of pestilence, maybe their meager harvests do not feed them or their families, or perhaps they do not have secure land tenure. In other instances, rural people are pulled to cities that they view as providing more economic and social opportunities. They are attracted by the idea and the promise of a better life. Whether they actually realize these benefits is another question. How do these causes differ across regions? Well, it depends upon the prosperity and environmental conditions of a given place, it particularly depends on the environmental conditions.

You’ve studied slum development through a historical perspective. What is unique about the causes and challenges of today’s growing slums?

The answer to your question on the most basic level is trajectory and scale. The speed with which slums and informal settlements are emerging today is faster than in the past. In the 19th century, London, the largest city in the world had large swaths of slums, a phenomenon well-documented by Charles Dickens’ novels and Charles Booth’s social surveys; however, its slums grew over a hundred year span. The growth of those we are witnessing today is taking place over a much shorter period. In the past twenty years, we have seen annual increases of slum dwellers in the Global South in the range of 18-20 million people. The scale of these slums is much greater than in the past as well. London grew from 1 million to 6.7 million in 1900. Today, the largest cities have populations of 20 or 30 million. And many cities in the Global South have half or more of their populations living in slums. Nairobi, for example, has a population of 3 million, with more than 1 million living in slums, the most notorious of which being Kibera. Joel Cohen’s chapter, “Human Populations Grow Up,” in my book Global Urbanization, calculates that to accommodate the expected urban growth, we will need to build the equivalent of a city of a million every week for the next forty years. This gives you a sense of the scale.

To deal with this growth, we need to pursue two strategies. The first strategy is to upgrade existing informal settlements—they need streets wide enough to accommodate basic services like water and sewer and to get a fire engine in, and so forth. We have to invest in these areas so that they become functioning places that can be integrated into the fabric of the city. The second strategy calls on us to think about the two and a half billion people who are going to be moving to cities. The question is, do we want them to be living in the slum conditions that has housed their predecessors? Of course not. So we must create the space for them to live. We need to be offering sites for their housing and laying out areas of public space for streets and basic community services. We should do this at scale. It’s a tough road, but it is the only reasonable thing to do.

Do you have a specific example of a city that integrated or upgraded slums well?

Well you can go back in history and believe it or not, Paris was a city that was filled with slums. Now, we might not like the solution that they came up with but we should learn from it so we can pursue the best practices and avoid the worst. It was done with a master solution: clean water, sewers, street systems, parks, new forms of higher density housing. The implementation was brutal, not a pattern we would follow today. Nonetheless, since the mid-19th century, Paris has been held up as a model city. A more contemporary example is Medellín, Colombia. This city engaged in what one of my colleagues, David Gouverneur, author of Planning and Design for Future Informal Settlements, calls “acupuncture.” You make strategic investments to improve mobility and public life with such things such as cable cars, public plazas, schools, health care centers and libraries. While displacement occurs, people are given new housing (likely in high rises) in the community. Additional development is connected to the existing upgraded areas, but laid out with the appropriate public space and services.  While this example illustrates the physical side of accommodating growth but we also have to remember that social investments are necessary as well. The Medellín case was preceded by public action that created safety in these neighborhoods.

The challenges facing women in slums are often different than those of men. How do we empower women in informal settlements?

Well I think we have to empower both men and women—everybody needs a job. For women in particular, there are some wonderful examples worldwide. A number of organizations help legitimize informal workers and their livelihoods. Women in Informal Employment; Globalizing and Organizing (WIEGO) is one. Another is Global Communities, an international non-profit, that crafted a program in Pune, India to transition female rag pickers into the formal economy by doing a couple of things. Number one was convincing the municipal government that they were a legitimate workforce doing a public service, who deserved recognition, wages and licenses. Number two, was finding places where the waste material that they were collecting could be sorted in a sanitary way. In general, we have to make sure that women’s personal safety and rights within domestic situations are protected—that’s clear. What we really have to do is to address poverty, because these kinds of terrible things happen to women and others largely because of poverty.

Global Communities worked to transition women rag pickers into the formal economy in Pune, India. Photo by Adam Cohn/Flickr

How does density play a role in revitalizing urban space and what are some policy tools for increasing density?

The word density usually has everyone raising their hands and saying “we don’t want it, thank you very much.” So, we have to deploy communication and educational programs to define different levels of density and their varied benefits. We have to demonstrate visually well-designed medium- and high-density arrangements. We have to show the advantages of higher density places, including their ability to support walkability, public transit and businesses. We have to show the economies of scale that higher density brings with regard to the provision of basic services.

Policy tools for increasing density encompass land use regulation, taxation and infrastructure investment. Land use regulation includes statutory master planning, zoning and growth boundaries. The former makes master plans legally binding, while the latter allows government to regulate the use and intensity of use of land. These tools allow the public sector to set density requirements. In addition, the zoning ordinance can incentivize density while calling for the provision of a public good. For example, in exchange for increasing the square footage of a building, the zoning ordinance can specify public open space contributions or transportation improvements. Finally, through master planning or legislation, government can create a growth boundary, beyond which certain land uses are barred. The boundary disallows new development beyond it and thus, forces development within it. Over time, the supply of land diminishes and rises in cost, supporting higher density development.

For these tools to be effective, they have to make a private investment pay; that is, they have to create a financially viable environment where the private sector—which will be building the density—will engage in the desired high density construction. Taxation is another strong tool to encourage density. At one extreme, the public sector can tax undeveloped land while at the other it can offer tax breaks for new construction that meets density goals. Infrastructure investment can make land more attractive for development. For example, when New York City transformed an obsolete elevated railroad track into a linear park now known as the High Line (and simultaneously changed the zoning to allow for high density mixed use development), developers “took the bait,” and invested in high density construction in the surrounding area. These are a few existing tools, but we must think of new ones. We have to experiment with them and then evaluate them. And don’t throw them out just because they don’t work on the first try, refine and perfect them.

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