Population Pyramids: Definition, Types, Stages

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  • 0:03 What Are Population Pyramids
  • 0:50 Types
  • 1:48 Stages
  • 3:09 Lesson Summary
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Lesson Transcript
Yolanda Williams

Yolanda has taught college Psychology and Ethics, and has a doctorate of philosophy in counselor education and supervision.

Expert Contributor
Grace Pisano

Grace has a bachelor's degree in history and a master's degree in teaching. She previously taught high school in several states around the country.

Did you know that there are five stages of population pyramids? In this lesson, learn more about the different types, and stages, of population pyramids as well as look at some examples.

What Are Population Pyramids?

Imagine you are a sociologist studying population growth in North America. Specifically, you are interested in examining the age and sex of the population. One way in which you can accomplish this goal is to create a population pyramid.

Population pyramids are graphical representations of the age and sex of a population. For this reason, population pyramids are also referred to as age-sex pyramids. We refer to these graphs as pyramids because they are usually shaped like triangles, though as we will see shortly, population pyramids also take other shapes. Population pyramids usually have males on the left side and females on the right. There is also a vertical line in the middle of the graph that separates the males from the females.


There are three types of population pyramids: expansive, constrictive, and stationary.

Expansive population pyramids depict populations that have a larger percentage of people in younger age groups. Populations with this shape usually have high fertility rates with lower life expectancies. Many third world countries have expansive population pyramids.

Constrictive population pyramids are named so because they are constricted at the bottom. There is a lower percentage of younger people. Constrictive population pyramids show declining birth rates, since each succeeding age group is getting smaller and smaller. The United States has a constrictive population pyramid.

Stationary population pyramids are those that show a somewhat equal proportion of the population in each age group. There is not a decrease or increase in population; it is stable. Austria has a stationary population pyramid.


There are five stages of population pyramids: high fluctuating, early expanding, late expanding, low fluctuating, and natural decrease.

The first stage is high fluctuating. High fluctuating population pyramids have wide bases and narrow tops, which indicates that there are few old people in the population and a high percentage of young people. These pyramids are also concave due to their high birth and death rates, and low life expectancies.

The second stage is early expanding. In this stage, people are reproducing at a higher rate than they die. Populations in this stage still have low life expectancies and high birth rates.

The third stage is late expanding. The top is still shaped like a pyramid; however, the bottom begins to level out as the birth rate becomes more stable and life expectancy continues to increase.

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Additional Activities

Deciphering and Mapping Population Pyramids

After learning about population pyramids, students will practice interpreting the graphs and drawing conclusions about world populations in this activity. Before beginning the activity, collect current population pyramids from about 15 countries in the world. Select from countries on different continents and in different stages of development.

Begin by hanging the population pyramids around the room. Then, explain to students that they will be interpreting the pyramids in a way similar to a gallery walk. On a piece of paper, they should record the name of the country, and then determine if it is expansive, constructive or stationary. Then, they should determine if the population is in the stage of high fluctuating, early expanding, late expanding, low fluctuating or natural decrease. They should use the tools they learned in this lesson to make the determination.

Once they have completed this for each of the chart, they should map the data. Using a key they create, they should color in the country on a world map based on the type of population (expansive, constructive or stationary). After doing this, students should see if they should draw conclusions about what types of countries have certain types of populations.

To get started, have students think about these questions:

  • Do the different types of population tend to occur in the same regions?
  • Think about political, social and economic trends. Are there any similarities in population type based on this?

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