Lesson Transcript
Instructor: Jessica Whittemore
Jessica has taught junior high History and college seminar courses. She has a master's degree in Education.
This lesson will seek to explain the concept of population density. It will focus on three specific measurements of density. They are arithmetic, physiological, and agricultural density.
Population Density
Besides the skyscrapers, the Broadway shows, and the plethora of yummy food choices, one of the most amazing things to me about New York City is the massive waves of people that are continually moving along its streets. Whether at three in the morning or three in the afternoon, the streets are always humming. With this massive amount of people, New York City is a great example of a place with a very high population density. Today we're going to take a look at this concept of population density.
Stated rather simply, population density is a measurement of the number of people in an area relative to its size. Like many geographical concepts, it's not an exact number. It's usually more of an average or even an estimate. With this in mind, population density is most often calculated by the number of people per square kilometer.
Population density is often measured in three different ways. There is arithmetic density, physiological density, and agricultural density.
Arithmetic Density
We'll get started with arithmetic density. Arithmetic density is what most people think of when they hear the word 'population density.' It's simply the total number of people divided by the total land area. Also called real density, arithmetic density does not take into account whether or not the land is rural, urban, or whether it is desert or frozen tundra. It just gives the straight-forward measurement of people divided by land. I like to think of it as just being simple arithmetic.
Physiological Density
With arithmetic density under our belts, let's take a look at physiological density. Physiological density is the number of people per unit area of arable land. Explaining this a bit, arable denotes land that is suitable for growing crops.
In other words, arable is much the same as being fertile. With this in mind, a simpler definition of physiological density might be the number of people divided by land that is suitable for growing crops. Physiological density is often used to estimate how long a land and its resources can sustain its population. Making this easy to hold on to, I like to think of physiological density as a look at how long the 'physical' land can support its people.
Agricultural Density
Last we come to agricultural density. Being sort of similar to physiological density, agricultural density measures the number of agriculturalists per unit area of arable land.