Population in Africa

Lessons

Senior 3 · Geography

Population in Africa

4 lessons

Lesson 1 of 4

Population Distribution, Density and Structure

25 min

Let's begin

Namibia is almost as large as Nigeria, yet in 2023 Nigeria had about 228 million people and Namibia about 3 million (Our World in Data, UN 2024). Rwanda, one of the smallest countries on the continent, counted 13,246,394 people in August 2022, at 503 people per square kilometre (NISR). In S1 you learnt how to read a pyramid and calculate density; in this lesson you will use those skills to explain the pattern across the whole of Africa.

Definition

Population distribution: the way people are spread over an area: crowded in some places, sparse in others. Population density: the average number of people per square kilometre: $\text{density} = \frac{\text{population}}{\text{area in km}^2}$ Population structure: the make-up of a population by age and sex, shown in a population pyramid.

Where Africa's people live

Africa had about 1.48 billion people in 2023 (Our World in Data, UN 2024), spread very unevenly.

Densely populated	Why	Sparsely populated	Why
Nile valley and delta (Egypt)	Water and fertile alluvium in a desert	Sahara and Namib deserts	Too little water
West African coast and southern Nigeria	Reliable rain, farming, ports, oil and trade	Congo Basin rainforest	Dense forest, leached soils, diseases, poor transport
Great Lakes highlands (Rwanda, Burundi, Uganda)	Two rainy seasons, cool healthy climate, fertile volcanic and lake-shore soils	Kalahari and the semi-arid Horn	Low, unreliable rain; mainly nomadic herding
Ethiopian Highlands; Kenya Highlands	Altitude gives a cool, wet climate	Tsetse-infested savanna in parts of central Africa	Sleeping sickness in people and cattle
Maghreb coast; Gauteng (South Africa)	Mediterranean farming; mining and industry	High mountains	Cold, steep, thin soils

The factors fall into two groups. Physical factors: rainfall and water supply, temperature and altitude, relief, soils, vegetation and disease. Human factors: mining, industry and towns that offer jobs; transport routes and ports; history (e.g. old kingdoms, colonial plantations and mines); and government policy, such as resettlement schemes.

Density in Rwanda

NISR reports that Rwanda's density rose from 183 people per km² in 1978 to 272 in 1991, 321 in 2002, 415 in 2012 and 503 in August 2022. By province, the City of Kigali has 2,401 people per km², the Western Province 693 and the Eastern Province, the least dense, 433. Among districts, Rubavu, at 1,614 people per km², is the most densely populated outside Kigali. The fertile volcanic soils of the north-west and the jobs and services of Kigali explain much of the pattern; the drier, more recently settled east is less crowded.

Mr. Sinn: Population Distribution and Density. The examples are worldwide; watch for the difference between arithmetic density (people per km² of all land) and physiological density (people per km² of farmland), and apply it to Egypt.

Population structure

Figure 1 shows Rwanda's structure in 2022 as percentages, so it can be compared with other countries of any size.

Figure 1: Rwanda's population pyramid, 2022.

Age group	People (NISR, 2022)	Share
0–14 (young dependants)	4,956,812	37.4%
15–64 (working age)	7,737,654	58.4%
65 and over (old dependants)	551,928	4.2%
Total	13,246,394	100%

Most African countries have an expansive pyramid like Rwanda's: a wide base from high birth rates, and a narrow top. Countries whose birth rates have fallen for decades, such as Mauritius or Tunisia, are moving towards a stationary shape, and many European countries and Japan have a constrictive one (Figure 2).

Figure 2: three typical shapes. Illustrative only.

Definition

Dependency ratio: the number of dependants (aged 0–14 and 65+) for every 100 people of working age (15–64): $\text{dependency ratio} = \frac{\text{people aged 0–14} + \text{people aged 65+}}{\text{people aged 15–64}} \times 100$ Sex ratio: the number of males per 100 females.

Worked example

Worked example 1: comparing densities. In 2023 Nigeria had 227,882,949 people on 923,769 km², and Namibia 2,963,102 people on 825,615 km². Calculate and compare their densities.

Nigeria: $\frac{227{,}882{,}949}{923{,}769} \approx 246.7$ people per km².
Namibia: $\frac{2{,}963{,}102}{825{,}615} \approx 3.6$ people per km².
Nigeria is about 69 times as dense, because its south has reliable rain, fertile land, oil and great cities, while most of Namibia is desert or semi-desert (the Namib and Kalahari).

Worked example

Worked example 2: dependency ratio. Use the table above to calculate Rwanda's dependency ratio in 2022.

Dependants: $4,956,812 + 551,928 = 5,508,740$ .
Ratio: $\frac{5{,}508{,}740}{7{,}737{,}654} \times 100 \approx 71.2$
So every 100 people of working age support about 71 dependants, most of them children. This is why schools, health care and jobs for young people are national priorities.

Warning

Density is an average. Egypt's density for the whole country hides the fact that almost everyone lives in the Nile valley and delta, and almost no one in the desert. Always say where people are concentrated, not just the national figure.

Tip

Reading a pyramid in three looks. The base (birth rate), the sides (death rate: steep sides mean many deaths at each age), and the top (life expectancy). Then compare the two halves: Rwanda's top has more women than men, because women live longer.

✦

Practice

Define population distribution and population density.
Name two densely populated and two sparsely populated regions of Africa, and explain one of each.
Rwanda had 13,246,394 people in 2022 on 26,338 km². Calculate its density to the nearest whole number.
From Figure 1, which age group is the largest for each sex?
What percentage of Rwanda's population in 2022 was aged 65 and over?
Describe the shape of Rwanda's pyramid and give two reasons for it.
Explain why Rubavu district is much more densely populated than most districts of the Eastern Province.
Using the NISR densities for 1978 and 2022, by how many times did Rwanda's density increase?

Show answersHide answers

Distribution: how people are spread over an area. Density: the number of people per km² (population ÷ area).
Dense, e.g. the Nile valley (water and fertile alluvium) and the Great Lakes highlands (reliable rain, fertile soils, healthy climate). Sparse, e.g. the Sahara (no water) and the Congo rainforest (dense forest, leached soils, disease).
$13{,}246{,}394 \div 26{,}338 \approx 503$ people per km².
0–4 for both males (6.5%) and females (6.4%).
$551{,}928 \div 13{,}246{,}394 \times 100 \approx 4.2\%$ .
Expansive: a wide base narrowing steadily to a small top. Reasons: high birth rates in recent decades; fewer people at older ages because of deaths at each age and lower life expectancy in the past.
Rubavu has fertile volcanic soils, reliable rain, a cool healthy climate, Lake Kivu for fishing and trade, and a border town (Rubavu–Goma) with jobs; much of the east is drier, with longer dry seasons, and was settled more recently.
$503 \div 183 \approx 2.7$ times (NISR says it "tripled" in round terms).

Sources and credits

National Institute of Statistics of Rwanda (NISR), Fifth Rwanda Population and Housing Census 2022, Main Indicators Report: executive summary (total, sex ratio, urban share), Table 5 (age and sex) and pages 3–4 (densities). Figures used as published.
Population of Africa, Nigeria and Namibia, 2023: Population, Our World in Data, based on UN World Population Prospects 2024, CC BY 4.0.
Areas of Nigeria and Namibia: Nigeria and Namibia, Wikipedia contributors, CC BY-SA 4.0.
Video: Population Distribution & Density, Mr. Sinn, embedded from YouTube.
Figures 1 and 2, explanations, worked examples and exercises: written and drawn by Ganzaa.

This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.

1Where Africa's people live

2Density in Rwanda

3Population structure

Where Africa's people live

Density in Rwanda

Population structure