The true drivers of urban growth in Africa: young populations, migration, and the rise of small cities

The Real Variables Behind Africa’s Urban Growth: Young Populations, Migration, and the Rise of Small Cities

A global study published in *Nature Cities* serves as a reminder that urbanization does not occur evenly. Based on estimates of age and sex structures in more than 10,000 cities from 2000 to 2020, the research team found significant differences in urban population change worldwide; of all urban growth, about 45% came from net migration and 55% from natural increase. More importantly, small cities have long been younger in age structure than large cities, and this phenomenon is especially pronounced in Africa.

For Africa’s development agenda, this is not merely a demographic conclusion, but a signal about productive capacity, infrastructure allocation, and the future center of growth. Different sources of urban growth imply different problems cities need to address: if population growth comes mainly from natural increase, the focus is on education, health, and housing; if migration accounts for a larger share, the priorities are employment, transportation, land development, and access to public services. For Africa, which is undergoing rapid urbanization, this distinction is especially critical.

What Happened

The study emphasizes that changes in urban population worldwide do not fit the intuition that “all cities are expanding in similar ways.” Instead, divergence among cities is widening:

• Globally, the ratio of children and older adults to the working-age population fell from 0.87 to 0.59, indicating that urban population structures are becoming more “working-age” overall;
• But differences among cities are substantial, especially as small cities in Africa remain significantly younger;
• Urban sex structures also show clear spatial differences, with some cities in the Middle East and North Africa experiencing a pronounced male surplus, reflecting patterns of labor migration;
• Urban population growth is not driven solely by natural increase; migration has become an important component of urban expansion.

This means that urbanization is not simply “population concentrating in cities,” but rather a redistribution of population across different city tiers, regions, and opportunity structures.

The Development Logic Behind This Change

From a development perspective, the most important lesson from this study is that cities are not abstract national averages; they are networks of cities with different functions, different population structures, and different economic roles.

Many African countries’ urban systems are under dual pressure. First, primate cities carry a large share of service, administrative, and consumer activity, but land, housing, transportation, and infrastructure are becoming increasingly constrained. Second, many small and medium-sized cities are playing a growing role in industry, logistics, and agricultural distribution, yet they have long faced insufficient data and inadequate public investment.

The Nature study specifically points out that small cities are neglected by policy in many regions, yet they are often not “small” in population terms and are especially young in Africa. Several real-world dynamics lie behind this phenomenon:1. Rural-to-urban migration first flows toward smaller and medium-sized cities with lower costs and lower barriers. These cities are often the first receiving points for regional employment and services. 2. High fertility rates and a young population structure mean that many African cities are still in a “population expansion” phase. This stands in sharp contrast to some high-income countries, where urban populations are stagnant or declining. 3. Differentiation in the urban hierarchy means uneven distribution of opportunities. If resources and investment are overly concentrated in capitals and major metropolitan areas, secondary cities will struggle to develop genuine industrial absorption capacity.

In other words, the key to urban growth in Africa is not simply that “cities are getting bigger,” but rather “which cities are absorbing growth, and what kind of growth they are absorbing.”

Implications for local development

This study has at least four direct implications for urban policy and development strategies in African countries.

1. Employment: younger cities mean greater pressure to create jobs

Smaller cities are younger, which means that over the next 10 to 15 years, the number of people entering the labor market will continue to grow. If manufacturing, construction, logistics, and urban services do not expand in step, cities will face problems such as youth unemployment, the expansion of informal employment, and income instability.

This is also why urban population structure should not be judged by total size alone. A city with the same population size, if it has a younger age structure and stronger migration inflows, needs more industries and services geared toward first-time job seekers.

2. Industrialization: small and medium-sized cities may become the landing ground for manufacturing and processing

In many African countries, land costs in large cities are higher, traffic is more congested, and room for expansion is more limited. By contrast, if small and medium-sized cities can receive support in electricity, roads, and industrial parks, they are more likely to take on light manufacturing, agro-processing, building materials, and regional warehousing functions.

The Nature study suggests that national average population structure should not be used to judge urban development potential. For industrial investors, cities with dense young populations, continuing migration inflows, but not yet overly saturated, may be better suited than traditional capitals to serve as new manufacturing hubs.

3. Infrastructure: service provision must shift from “average coverage” to “tiered provision”

The study points out that the lack of reliable and consistent city-level population data limits infrastructure and public policy planning. This is especially important in Africa, where many small and medium-sized cities have infrequent data updates, and planning for housing, water supply, sanitation, roads, and public transport often lags behind population change.

If urban growth is driven mainly by migration, infrastructure demand will be concentrated more in the following areas:

• transport connections and commuting efficiency;
• low-cost housing;
• drainage and water supply systems;
• markets, warehousing, and wholesale logistics;
• vocational education and skills-training facilities.

This kind of infrastructure is not “urban beautification”; it is the economic foundation for improving productivity and reducing transaction costs.

4. Urban governance: changes in population structure will affect social stability and public financesThe study also reminds us that cities with a high share of young people are more likely to experience social pressure when employment, housing, and public services are insufficient. For African countries, this does not mean that “a young population is a risk”; rather, it shows that if cities cannot turn population growth into productivity, the demographic dividend will become a governance burden.

Implications for Regional Development

African urbanization has never been a process confined within a single country; it is closely tied to cross-border trade, regional supply chains, and labor mobility.

1. Secondary cities may become nodes along regional corridors

Many African secondary cities are located near trade routes, ports’ hinterlands, cross-border highways, or major agricultural production zones. As populations continue to become younger and flow in, these cities may no longer be merely “county seats,” but will gradually evolve into regional nodes of logistics, processing, and consumption.

2. Urban networks will affect the implementation efficiency of AfCFTA

Whether the African Continental Free Trade Area can truly expand regional markets depends not only on tariff policy, but also on whether efficient logistics, warehousing, finance, and digital payment systems exist between cities. Young and growing small and medium-sized cities, if supported by infrastructure, can become intermediate links in regional industrial chains.

3. Population mobility will reshape cross-border labor markets

The gender-structure differences in the study, especially the male surplus in some regions, suggest that cross-border labor migration and employment structures by industry will continue to affect regional economies. For labor-intensive sectors such as construction, mining, transportation, and services, urban population structure will directly affect labor supply.

Potential Impacts Over the Next 5 to 15 Years

From a medium- to long-term perspective, the most important value of this study is that it changes the way we understand African growth.

Over the next 5 to 15 years, at least three trends deserve attention:

First, the center of urban growth may continue to spread toward small and medium-sized cities

If large cities continue to face bottlenecks in housing and infrastructure, some growth will spill over to surrounding cities and regional centers. Whoever can first provide electricity, roads, land development, and market access is more likely to become a new growth pole.

Second, whether the demographic dividend can be realized will depend on cities’ absorption capacity

Africa’s young population does not automatically bring growth. Only when cities can provide stable jobs, skills training, and productive investment will young people be transformed into consumer demand, entrepreneurial vitality, and a broader tax base.

Third, infrastructure investment will depend more on a “population structure map” than on administrative boundaries

One of the real significance of this study is that it pushes public investment to shift from allocation “by administrative level” to allocation “by actual population structure and migration routes.” In the future, if investment in power, telecommunications, transportation, and housing cannot keep pace with urban population change, it will be misallocated and drag down regional competitiveness.

ConclusionThis study does not tell us that African cities will automatically prosper; what it tells us is that the sources of urban growth, age structure, and hierarchical distribution are determining the true limits of Africa’s future growth. For Africa, this represents an important shift in its long-term development path: urbanization is no longer just the expansion of capital cities, but a development process jointly shaped by medium and small cities, young populations, and migration networks.

If there is a key inflection point in Africa’s growth story over the next decade, it is very likely not the singular rise of one megacity, but whether the network of cities that continues to attract young people can be transformed into systemic capabilities for industrialization, regional connectivity, and productivity gains.