Overpopulation happens when there are too many people for the available resources. This can lead to overcrowding, high unemployment, food shortages, and pressure on housing, education, and healthcare systems.

Underpopulation is the opposite — when there are too few people relative to the country’s available resources. This often appears as labour shortages and slow economic growth.

Causes and Consequences of Overpopulation

Overpopulation can result from high birth rates, falling death rates, or inward migration. It’s often seen in countries where fertility rates remain high and infrastructure development can’t keep up.

The consequences include:

• Increased pollution and waste
• Pressure on public services
• Rising unemployment
• Food and water insecurity
• The growth of informal settlements, or slums
  

Informal Settlements: What Drives Them?

One major cause is rural-to-urban migration. Cities grow faster than they can expand housing or services. As a result, many low-income migrants settle in informal housing without legal titles, water access, or sanitation.

In China, major cities like Beijing and Shanghai have drawn millions of rural migrants. Cities offer jobs, education, and better living standards — but not enough affordable housing.

This has led to the rise of urban villages and informal settlements. These areas are often overcrowded and under-serviced. Migrant workers living there may face discrimination and be excluded from official city services due to hukou (household registration) restrictions.

These communities often face social exclusion. Residents may struggle to access schools, healthcare, or jobs. In some cases, they’re even left off official maps.

Case Study: Kibera, Nairobi

Kibera is one of Africa’s largest informal settlements. It grew rapidly due to migration from rural Kenya, as people moved in search of better jobs and services.

Today, Kibera faces challenges like overcrowding, poor sanitation, unreliable electricity, and limited access to clean water. Still, it remains home to vibrant communities, small businesses, and local resilience efforts.

Full Population Revision Pack available