Population is defined as the number of people living within a specific geographic region.$^0$
The way in which the population is spread over a given region is called population distribution. Population distribution is studied on local, regional, national, and global levels. The pattern of distribution is generally uneven.$^0$
For example, in the US the majority of the people live in the cities. Even within these cities are areas of higher and lower density. More people live in apartment complexes than in independent houses in these cities.$^5$
Population distribution may come about naturally, but it can also be influenced by government policy.$^0$
Population density is the average number of people living in a given area. It allows you to compare two areas to understand the overall population distribution.$^0$
It is given by the formula: $^0$
$$ PD = \frac{P}{A} $$
Where PD is population density, P is the total population, and A is the total land area in square km.\
The popula density of the US
There are four general components of population change: $^2$
We can use these components to understand the population change itself.