| Category | Crude birth rate | Crude death rate |
|---|---|---|
| 1900 | 38 | 30 |
| 1930 | 37 | 20 |
| 1960 | 30 | 12 |
| 1990 | 16 | 10 |
| 2020 | 11 | 10 |
Population pyramids and the demographic transition: a free drill
Read the pyramid, name the stage, then change the birth and death rates and watch the shape answer. Every number on this page is computed as you go: the rate of natural increase, the doubling time by the rule of 70, and the dependency ratio.
Which stage of the demographic transition does this pyramid most likely show?
Move the rates and the pyramid redraws to the shape a population settles into when they hold for generations.
- Natural increase
- 2% a year
- Doubling time
- About 35 years
- Dependency ratio
- 72.1
- Closest stage
- Stage 2
(30 − 10) ÷ 10 = 2%; 70 ÷ 2 ≈ 35 years. Death rates have fallen but birth rates are still high, so the population grows fast.
| Rate of natural increase | (birth rate − death rate) ÷ 10, in percent |
|---|---|
| Doubling time | 70 ÷ the growth rate in percent, in years |
| Dependency ratio | People under 15 and 65+ per 100 aged 15 to 64 |
| Unit 2 weight | 12–17% of the multiple choice |
What each stage looks like
- Stage 1: high birth and death rates, little growth. No country fits it today.
- Stage 2: death rates fall while birth rates stay high. The pyramid has a wide base and narrows quickly: fast growth.
- Stage 3: birth rates fall as more people live in cities, children cost more to raise and women stay in school and work. The base is still broad but no longer much wider than the bars above it.
- Stage 4: low birth and death rates. The pyramid's sides are close to straight until late middle age.
- Stage 5, where the model includes it: birth rates below death rates. The base is narrower than the middle and the population ages and may shrink.
What the exam asks
Questions show a pyramid or a table of birth and death rates and ask for the stage, a consequence (a large dependent population, a shortage of workers, a need for schools or for elder care), a policy a government might choose (pronatalist or antinatalist), or a limitation of the model, which was built from the history of European countries.
Try 2 questions
| Age group | Population (millions) |
|---|---|
| Under 15 | 18 |
| 15 to 64 | 60 |
| 65 and over | 12 |
Next step
College Board's AP Human Geography course page, with the unit weights
Questions people ask
How do you find the stage of the demographic transition from a population pyramid?
Look at the base and the sides. A wide base that narrows quickly is stage 2; a broad base that narrows steadily is stage 3; nearly straight sides are stage 4; a base narrower than the middle is stage 5.
How do you calculate doubling time?
Divide 70 by the annual growth rate in percent. A country growing at 2% a year doubles in about 35 years.
What is the rate of natural increase?
The crude birth rate minus the crude death rate, both per 1,000 people, divided by 10 to give a percent. It ignores migration.