Population Pyramids
and
Population Density Maps
Population
• Two useful ways that geographers can
graphically display population
information include:
• Population Maps to depict population
density
• Population Pyramids to depict
population distribution
Population Density…
• …is a measure of how many people live
in a certain unit area
• Take the population of a region and
divide it by its square area
• Ex.: The population density of Texas
is 79.6/mi²
• On average, 79.6 people live in a
square mile in Texas
One type of population map shows
one dot for every certain number of
people who live in a place:
Another type shows population as
color coded regions:
Population Pyramids
• A population
pyramid is a bar
graph, usually in
the shape of a
pyramid, used to
compare different
age groups of men
and women.
Population Pyramids
• These graphs show how a population is
distributed between age groups and sexes
by percentages or numbers.
• Lower age groups are at the bottom
• Men are left of center
• Women are right of center
• In this pop. pyramid, the majority of the
population is young, because there is a high
birth rate and a high death rate
India, year 2000: large young population,
high birth rate, high death rate
India, year 2025: death rate decreases,
the younger population grows older
India, year 2050: the population has
bulged in the 25-39 age groups
China:
19502050
South Korea’s Population Boom
The Aging of Japan
Low Death Rate and Dropping Birth Rate
Triangle
• Developing
• Rapid Growth
Box
• Developed
• Slow Growth
Modified box, glass or cup
• Higly Developed
• Negative Growth
Population Growth
Theories
Malthusian Theory
• In 1798 Thomas Malthus
published his theory
• The population will continue to
grow until it surpasses the food
supply
• People will starve reducing the
population back to a sustainable
level
Neo-Malthusian Theory
• The population is growing faster than
Malthusian anticipated
• Beyond the capacity of food and:
• Clean air
• Living space
• Fuel
According to these theories, a
catastrophe is imminent to reset the
population
• Evidence:
• Starvation in Africa
• Loss of farmland in
China, South
America, and Africa
• Natural disasters
worldwide
• World population since 500
A.D.
What do you think is going on in
each U.S. city? Write down your
guesses in your important books.