Researchers at the University of Chicago have produced a comprehensive dataset mapping over 415 million buildings across 50 countries in sub-Saharan Africa. The study, published in Nature, provides detailed analysis of urban development at the street block level and highlights areas where infrastructure and public service access are lacking.
The research uses high-resolution data to evaluate street access for each building on the continent. This approach links infrastructure connectivity with established measures of development, such as water and sanitation services, education, and economic opportunity.
“When you look at developed cities you see something universal: Every building has street access, no matter if your city is a grid like Chicago or curvy like Rome,” said Luis Bettencourt, a UChicago professor of ecology who led the study. “These connections give people access to water, sanitation and garbage disposal, and an address to register for school or where the fire department can find them in an emergency.”
Bettencourt noted that many rapidly growing cities face challenges in extending necessary infrastructure to informal settlements or slums. “These disconnections lead to a range of problems for residents, holding back their development and that of their cities,” he said. “This paper shows how we can measure and then begin to address those deficits for each household in every building, anywhere in the world.”
The United Nations estimates that more than 1.1 billion people live in informal settlements globally without basic services. In response to this issue, poverty reduction and slum eradication were included as Sustainable Development Goals by the UN in 2015.
One method discussed is "localization," which focuses on improving conditions at the neighborhood level by targeting specific places and households. Using data from every building and street, Bettencourt and co-author Nicholas Marchio—a research data scientist at UChicago’s Urban Science Lab—demonstrate that this approach can be applied down to individual blocks.
Their work combined Ecopia’s full census of buildings in sub-Saharan Africa with OpenStreetMap street network data and other demographic information to create the Million Neighborhoods Africa map. This interactive tool allows users to view infrastructure access estimates for each building along with population statistics.
To assess accessibility, Bettencourt and Marchio calculated each building’s shortest path to a street boundary within its block. The maximum number of buildings one must pass through from the least accessible building defines block complexity—termed k complexity. Lower k values indicate better-planned blocks; higher values suggest less accessibility.
A formal city block typically has a low k value (one or two), while blocks with higher values (three or four) are less accessible due to longer access roads. Across sub-Saharan Africa, average block complexity is eight.
“This research provides the first comprehensive dataset of population and development indicators for all street blocks in sub-Saharan Africa, alongside open-source tools to extend the data globally in a standardized and comparable manner,” Marchio said.
“For countries that lack timely and reliable spatial data at the neighborhood level—which is essential for everything from service delivery to basic demography—this research fills a critical gap.”
The study also examined correlations between block complexity and human development factors such as education, health outcomes, housing quality, and crowding. Findings showed that neighborhoods with higher levels of disconnection tend to fare worse on these measures.
While major peri-urban settlements often lack services visibly, smaller pockets with high complexity also exist within otherwise developed areas. Improving physical access can benefit these communities by connecting them more closely with social and economic opportunities available elsewhere in their cities.
Bettencourt emphasized advances made possible by new urban science methods: “Developing cities have a lot of challenges to face, especially striving for greater prosperity and quality of life in the face of climate change. What is different now is that we can use advances in urban science and amazing new data to accelerate sustainable development,” he said.
“In this way, we can learn something profound about how all cities develop. What makes a good city? And how do we create more effective and organic solutions to problems of development that preserve culture, preserve people's dignity and preserve the history of each place?”
Support for this research came from the Mansueto Institute for Urban Innovation as well as the Susan and Richard Kiphart Center for Global Health and Social Development at UChicago.