AP® Human Geography review sheet from Aim for Five (aimforfive.com/geo/units/2/2-9)
Unit 2 · Topic 2.9
2.9 Aging Populations
A population ages when birth rates fall and people live longer. An aging population changes a country's politics, economy and society, and the dependency ratio is the main tool for measuring the strain.
Key terms
- aging population
- dependency ratio
- life expectancy
- pension
- labor shortage
Why populations age
Two forces make a population older. Falling birth rates mean fewer young people entering at the bottom of the pyramid. Rising life expectancy, the average number of years a newborn can expect to live, means more people reach old age and stay there longer. Emigration of young adults can speed up aging in the places they leave.
Japan is the clearest example. Close to 30% of its people were 65 or older in 2024 (Japan Statistics Bureau), and deaths have outnumbered births nearly every year since the mid-2000s. Italy, South Korea and Germany are also aging fast, and China is aging quickly because its birth rate dropped so sharply.
The dependency ratio
The dependency ratio compares the people usually too young or too old to work with the working-age population. Geographers usually count children under 15 and adults 65 and older as dependents, and people aged 15 to 64 as working age.
Dependency ratio = (people aged 0–14 + people aged 65 and older) ÷ people aged 15–64 × 100.
A ratio of 50 means there are 50 dependents for every 100 working-age people. Young, fast-growing countries have high ratios because of many children. Aging countries have rising ratios because of many retirees. Splitting it into a youth ratio and an elderly ratio shows which group is driving it.
Consequences of aging
- Economic: fewer workers pay taxes while more retirees draw pensions and need health care. Labor shortages appear in fields like construction, nursing and farming.
- Political: older people are a large and reliable voting group, so pensions and health care become major political issues. Governments face hard choices about raising taxes, cutting benefits or raising the retirement age.
- Social: families take on more elder care, and demand grows for nursing homes and home health workers. Schools in rural areas close as children become scarce.
- Spatial: in rural Japan, many villages are emptying, and millions of homes stand vacant.
How countries respond
- Raising the retirement age so people work and pay taxes longer.
- Encouraging more immigration to add younger workers.
- Pronatalist policies to raise future birth rates (topic 2.7).
- Using automation and robots, including in elder care, as Japan has tested.
- Getting more women and older adults into the workforce.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
Calculating a dependency ratio
A country has 12 million people aged 0–14, 60 million aged 15–64, and 18 million aged 65 and older. Calculate the dependency ratio and explain one consequence.
Show the solutionHide the solution
- Step 1: Add the dependents: 12 million + 18 million = 30 million.
- Step 2: Divide by the working-age group and multiply by 100: 30 ÷ 60 × 100 = 50.
- Step 3: Look at the mix: older dependents (18 million) outnumber children (12 million), so aging is driving the ratio.
- Step 4: Explain a consequence: each 100 workers support 50 dependents, mostly retirees, which strains pension and health care budgets paid for by workers' taxes.
Answer: Dependency ratio = 50 (50 dependents per 100 working-age people). Because most dependents are elderly, the government faces rising pension and health costs with a shrinking share of taxpayers.
Common mistakes
- Counting only older people as dependents. The ratio includes children under 15 too.
- Assuming a high dependency ratio always means an aging country. Young, fast-growing countries also have high ratios.
- Listing consequences without labeling them. Say whether an effect is political, economic or social.
On the exam
- Free-response parts often ask for one political, economic or social consequence of aging; give a specific one and explain why it happens.
- You may be asked to use a pyramid to identify an aging population; point to the narrow base and wide top.
Connected topics
Videos
Check yourself
4 questions on 2.9 Aging Populations. Pick an answer to see if you got it, and why.
Which of the following would most directly reduce the strain an aging population places on a country's pension system?
In several aging countries, voters over 65 make up a growing share of the electorate. Which political effect is most likely?
Japan has a very low birth rate and one of the world's highest shares of people over 65. Which of the following has been a response to labor shortages in industries like elder care and construction?
Which combination of trends causes a population to age most rapidly?
0 of 4 answered