Population Pyramids &

Demographic Transition

Developed vs. Developing By

Patricia Bailey-Jones

 Geographers use a variety of tools to help us understand population patterns in developed and developing countries.  Population pyramids  Demographic transitions

Population Pyramids

Definition

 A population pyramid shows the percentage of males and females by age group in a country’s population.

 Population pyramids help us understand population trends

Interpreting Shape  Pyramids take different

shapes based on the composition of a population

 Each type of shape tells us something about the place or country being graphed

Developing Countries  A common

shape among the world’s developing countries is a pyramid or triangle

 These countries show a high birth rate and a declining death rate.

 The majority of the population is very young, while only a small percentage lives to an old age – pop growing rapidly

Developed Countries  These countries

generally have a more rectangular shape

 The percentage of young people tends to be much smaller, causing the population to grow much slower

 Developed countries are highly urbanized and have relatively low birth rates and low death rates.

USA 1960

 A recent increase in births will also be reflected in a certain shape.

 Baby Boomers!

Cohorts

  If we talk about people born in a specific year or range of years, we call the group a “birth cohort”, or simply cohort.

 The baby boomers is a cohort of persons born between 1945-1960.

Missing Populations???

  This pyramid show the effects of major wars. Males are more likely than females to be killed during war times.

10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 2.00% 4.00% 6.00% 8.00% 10.00%

00-04

10-14

20-24

30-34

40-44

50-54

60-64

70-74

80+

Males

Females

Interpret the Shape

Interpret the Shape

 Madison Wisconsin 1980  Note the large bulge in the population around

the ages of 20 – 30.   In this city of 170,000, there is a University

with 40,000 students.

Interpret the Shape

Interpret the Shape

 Sun City, Arizona 1980  Note the bulge in the population of elderly

people.  This city was developed to attract older

persons who have retired from the labor force.  Many of the younger age groups are so small

that they don’t even appear on the graph.

Interpret the Shape

Interpret the Shape

 Aleutian Islands, 1980  Note the large bulge in the population of

young male workers  Some areas attract predominately male

workers.  This is a fishing community located in a very

harsh environment.

Demographic Transitions

Demographic Transitions

 The demographic transition is a model that shows how birthrates and death rates dropped in many countries as they developed modern economies

Most of the world’s richest and technologically advanced countries have experienced a “transition” from high birthrates and death rates to low birth rates and death rates.

 Many of the world’s poorer countries are now in the middle of similar changes

 The shift in growth rate with development has been called the demographic transition

Demographic Stages   Stage 1

 High Birthrate  High Death rate  High infant

mortality rate  Population

neither grows or really decreases

 Mostly agricultural

 Developing Country

Demographic Stages   Stage 2

  High Birthrate   Falling Death

rate   Falling infant

mortality rate   High population

growth rate   More advanced

farming technologies

Demographic Stages   Stage 3

  Low Birthrate   Low Death rate   Low infant

mortality rate   Slow population

growth rate   Industrialized

nations with advanced economies

  Developed countries

Demographic Stages

  Stage 4   Birthrates equal or

decline below the death rate, thus reaching zero population growth rate

  Total population slowly decreases