The Population Pyramid—what it is and how it works

Bar graphs are a handy way to illustrate numbers. For example, if we were to graph the number of males and females in Canada for various age groups according to the 1961 Census, the result would be the illustrations below.

<

If we were to display these graphs horizontally, make a mirror image of the one for women, and then join them together, we would have a population pyramid—exactly as seen below.

This population pyramid shows at a glance the distribution of the Canadian population in 1961.

You can see that the pyramid narrows toward the top. This is because the death rate is higher among older people than among younger people.

There are also a few bulges and narrower parts in the middle part of the pyramid. For example, there are not as many people in their 20s as in their 30s in Canada in 1961. The people in their 20s in 1961 were born during the Depression, a time of economic hardship in Canada when people were having fewer children.

In 1961, the pyramid had a wide base. In fact, when we add the percentages for the three lowest age groups, we find that 35% of the population was under 15. These are the “baby boomers,” a large group of people born between 1947 and 1966 when the economy was growing and prospering.

By analysing population pyramids and identifying trends, we can learn a lot about our society. These statistics give governments and others one of the tools they need to make informed decisions that will affect our lives today and in the future.