The Cost of Urban Sprawl: How Africa’s Density Choices Could Reshape Its Development Future

Africa’s urban population could double to 1.4 billion by 2050, making planned density critical to controlling infrastructure costs, land consumption and pressure on essential services. Governments, development partners and investors must act early on housing, transport, municipal finance and land-use planning to turn rapid urbanisation into sustainable economic growth.

Africa is entering an urban transformation that could reshape its economy, environment and development prospects for decades. Research by the OECD's Sahel and West Africa Club Secretariat (OECD/SWAC), the e-Geopolis Institute and associated research institutions projects that the continent's urban population will roughly double from about 700 million in 2020 to 1.4 billion by 2050. The critical issue is no longer whether African cities will grow, but whether governments can manage that growth before expanding settlements make infrastructure, housing and basic services far more expensive.

Africa Faces a 179,000-Square-Kilometre Urban Choice

The report examines three possible futures based on urban density. Africa had around 175,000 square kilometres of urbanised land in 2020. Under a high-density scenario, this could rise to about 271,000 square kilometres by 2050. If current density levels broadly continue, the footprint could reach 337,000 square kilometres, while low-density development could push it to 450,000 square kilometres.

That leaves a difference of around 179,000 square kilometres between the compact and sprawling scenarios, roughly equivalent to Africa's entire urban footprint in 2020.

Regional differences are substantial. Central Africa's urban surface could grow to 3.43 times its 2020 size under low density, compared with 1.86 times under high density. In West Africa, the range is between 3.24 and 1.68 times, while Nigeria ranges between 2.73 and 1.58 times.

For governments, these figures highlight the need to integrate population projections with land-use decisions. Development partners financing infrastructure will also need to consider not only how many people a project serves today, but where future urban populations will actually settle.

Expanding Cities Could Redraw Africa's Economic Map

Urban sprawl could transform separate towns into enormous metropolitan regions. Under low-density development, the study projects 1,552 mergers between urban agglomerations by 2050, compared with 1,123 under constant density and 771 under high density.

The Lagos-Ibadan-Cotonou corridor illustrates what this could mean. Low-density expansion could create more than 200 kilometres of near-continuous urban development, compared with around 115 kilometres under high density. The number of merged agglomerations could increase from 27 to 155, while their combined urban footprint could exceed 10,000 square kilometres.

Such corridors could create larger labour markets, strengthen logistics and expand opportunities for manufacturing, retail, housing and services. But infrastructure and governance would have to cross municipal and, in some cases, national boundaries.

International development institutions could therefore increasingly support metropolitan transport, regional infrastructure and cross-border planning instead of treating individual cities as isolated investment areas.

Sprawling Cities Come With a Bigger Infrastructure Bill

Density has major consequences for public finances because dispersed populations require longer roads, pipelines, electricity networks and communications systems.

The report uses Niamey, Niger, as an example. With its population expected to increase by around one million by 2050, infrastructure investment for newly urbanised areas could average approximately USD 44 million annually under low-density development, compared with around USD 32 million under high density. These estimates cover capital costs and exclude maintenance and continuing service delivery.

Density also affects basic services. Evidence cited in the study shows that about 42% of urban residents currently have piped water access and 22% have wastewater services. With population doubling, coverage could fall to around 40% and 20% respectively under low density, compared with 46% and 25% under high density.

For private investors, rapid urbanisation creates opportunities in affordable housing, construction, water, sanitation, renewable energy, public transport, digital infrastructure, logistics and geospatial technology. The risks include unclear land ownership, weak municipal finances and poorly planned expansion.

Planning Before Expansion Could Save Billions Later

The report does not advocate maximum density. Overcrowded neighbourhoods without adequate housing, infrastructure or green space can be damaging. Instead, policymakers should pursue planned and serviced density, while preparing in advance for unavoidable outward expansion.

Agricultural land requires particular protection because cropland is the land category most affected by future urban growth. Poorly managed conversion could threaten livelihoods, intensify land disputes and increase food-security pressures.

A major obstacle is limited planning capacity. Countries experiencing the fastest urban growth have only around one urban planner per 100,000 inhabitants, compared with 21.5 per 100,000 in OECD countries. Of 62 urban plans across 47 African countries with a 2020 target date, only six saw growth broadly aligned with their plans.

Governments therefore need stronger municipal finances, digital land records, satellite-based monitoring, clearer land regulations and better coordination between national and local authorities. Development partners can support planning capacity, infrastructure preparation and municipal financing, while private companies can bring investment and technology.

With another 700 million people expected to join Africa's urban population by 2050, delaying these decisions could be costly. The opportunity is to plan the roads, services, housing and economic centres before cities reach them, turning Africa's urban boom into an engine of productivity and inclusion rather than an expensive race to catch up.