Shaping Sustainable Urban Growth

As the world has become increasingly urbanized, what share of the earth’s land do cities use? A recent World Bank report, Pancakes to Pyramids: City Form to Support Sustainable Growth, analyzes city development to identify the spatial extent of cities, the drivers of urban growth and ways to influence those drivers to create more productive and sustainable cities.

In a major new finding, the report shows an increase in density in cities as the world becomes more urban. Using new data and analytical methods, the report explains the recent city growth of nearly 10,000 cities around the world along three dimensions: outward (horizontal sprawl), inward (urban infill), and upward (vertical growth in the form of taller buildings). Using these measures, the report describes city form along an idealized spectrum that ranges from mostly outward (pancake-like city form) to mostly inward and upward (pyramid-like city form).

It finds that, over the 1990-2015 period studied, cities with lower productivity, lower incomes, and less supportive public policies tended to sprawl, forming “pancake” cities characterized by smog, congestion, and crowded housing—think urban slums on the periphery of sprawling cities. In contrast, cities with higher productivity tended to grow denser and taller; higher demand for floor space by firms and households—supported by plans, policies, and investments—resulted in more infill development and more vertical layers, especially at the city center, as compared to cities in lower-income countries.

The report is significant for a number of reasons:

• Its use of the “Degree of Urbanization” approach to defining cities, which uses an internationally consistent measure of urban growth developed by the European Commission and endorsed in March 2020 by the United Nations Statistical Commission that is consistent across nations (for more on the Degree of Urbanization, see Lewis Dijkstra’s article in the October 2020 issue of Urban Link).
• Its reliance on floor area to measure city growth and form; rather than looking only at developed land area (which captures only outward growth), the report analyzes growth in terms of floor area (thereby capturing inward and upward growth as well).
• The empirical research shows in detail how the physical form of a city relates to economic development, especially income. It reports that growing cities in lower-income countries experienced much less infill (9%) than horizontal (91%) growth while growing cities in higher-income countries experienced a higher proportion of infill (35%) to horizontal (65%) growth. It also reports a strong relationship between productivity and vertical growth, showing that higher incomes and productivity support vertical growth, which is more capital-intensive.

Pancakes to Pyramids describes a virtuous cycle in which city plans and policies can support livable density and greater productivity. Providing a rich understanding of how a city’s physical form evolves in multiple dimensions and how that evolution influences and is influenced by market dynamics, the report suggests to decision-makers more tools with which to shape cities—including strategies to reform urban land markets and strengthen land use planning, improve infrastructure planning and investment, and mobilize urban finance.

Three of the report’s co-authors—Somik Lall, Lead Urban Economist and Global Lead for Territorial and Spatial Development, Urban, DRM, Resilience and Land; Mathilde Lebrand, Economist, Chief Economist Office for Infrastructure, The World Bank; and Daniel Sturm, Professor of Economics, London School of Economics—presented report findings at a September 17 online event. “City Form for Sustainable Growth,” is part of the Global Urban Development Pathways series organized by Penn IUR Faculty Fellow Gilles Duranton, Dean's Chair in Real Estate Professor, The Wharton School, University of Pennsylvania. Sameh Wahba, Global Director, Urban, Disaster Risk Management, Resilience and Land Global Practice, World Bank introduced the event’s presenters. Following their presentations, Solly Angel, Program Director of Urban Expansion and Professor of City Planning, NYU Marron Institute; Edgar Pieterse, Director, African Centre for Cities, University of Cape Town; Shipra Narang Suri, Chief, Urban Practices Branch, UN-Habitat; and Duranton discussed the report’s implications.

Visit the Penn IUR website for a recording of the event.