Population Growth

Factors Affecting Population Growth

According to demographers — people who study the growth, density, and other characteristics of the population — there are three major factors that affect population growth. These factors are fertility rate, life expectancy, and net immigration levels. Let's take a look at each one individually to get a better understanding of their impact on population growth.

Factors Affecting Population Growth: Fertility

The Fertility Rate is the number of births that 1,000 women are expected to go through in their lifetime. For example, a fertility rate of 3,500 would be equivalent to 3.5 kids per woman. The fertility rate is often compared to the number of deaths in a given year to get the replacement rate — the rate at which the number of births offsets the number of deaths.

If the United States has a high fertility rate, then the population growth will increase accordingly unless it is offset by the death rate. In the past, the United States had a higher fertility rate than it does today. The high fertility rate in the past can be attributed to families needing more children to add to family income. This rate has decreased in recent times since the need for young children to work has decreased.

Factors Affecting Population Growth: Life Expectancy

Life Expectancy is the average lifespan that a person will reach. In the United States, life expectancy has grown over time — developments such as medical advancements and safer working conditions have contributed to this. The greater the life expectancy, the larger the population will grow; the lower the life expectancy, the less the population will grow. Life expectancy can be impacted heavily by external factors such as genetics, lifestyle, and crime rate.

Factors Affecting Population Growth: Net Immigration

The Net Immigration Rate is the total change in population from people moving in and out of the country. In the United States, the net immigration rate tends to be positive — more immigrants come in than leave the United States. If a country were to have a negative net immigration rate, then more immigrants would be leaving the country than coming in. A positive net immigration rate will contribute to higher population growth, whereas a negative net immigration rate will contribute to lower population growth. The net immigration rate can be impacted by external factors such as the government's immigration policies and regime.

Population Growth Types

Let's go over the different population growth types. There are two different types of population growth: exponential and logistic.

Population Growth Types: Exponential

Exponential growth rate is growth that increases rapidly with passing time. In a graph, exponential growth increases upward and has a "J" shape. Let's take a look at a graph:

Figure 1. Exponential growth, StudySmarter Originals

The graph above shows us what exponential growth looks like over time. Population size increases by a larger amount with each passing year. The result is a "J" shaped curve with a rapidly increasing population growth rate.

Population Growth Types: Logistic

Logistic growth rate is growth that slows down with passing time. In a graph, logistic growth rate increases and then flattens out, resulting in an "S" shaped curve. Let's take a look at a graph below:

Figure 2. Logistic growth, StudySmarter Originals

The graph above shows us what logistic growth looks like over time. Population growth initially increases, then levels out after a certain point in time. The result is an "S" shaped curve and a slower population growth rate.

Population Growth and Economic Growth

Population growth and economic growth are closely related to one another. For example, productivity is an important factor in economic growth. How might productivity be important to population growth?

Economic Growth and Decline, pixabay

Population Growth's Economic Effects

Population growth will have many economic effects — both positive and negative.

Let's first take a look at population growth's positive economic effects.

Population Growth's Economic Effects: Positive Effects

Greater population growth can result in economic growth. More people in a country means that there is more access to labor; more access to labor results in more goods being produced and demanded — resulting in economic growth! More people in a country will also result in higher tax revenues for the government. The government can use the increased tax revenue on building infrastructure or improving welfare programs. Lastly, a higher population increases the probability of innovation in the free market.

Population growth's positive economic effects are clear — more people can yield more output, tax revenue, and innovation in the market. With these outcomes, why wouldn't a country push for high population growth?

Let's now take a look at population growth's negative economic effects.

Population Growth's Economic Effects: Negative Effects

Greater population growth may exacerbate the problem of resource scarcity. If a country is barely providing resources to its current population, what will happen if there is an exponential growth in population? People will not be able to access resources since there will be too many people demanding too few resources. Population growth can also put pressure on certain areas where people migrate to, such as cities. Cities tend to have more people living in them as opposed to rural areas; as such, cities can become overburdened with too many people living in them. Traffic congestion and pollution are often problems in these areas.

As you can see, there is much to consider when it comes to the economic effects of population growth. There is no clear economic outcome with population growth as no two countries are the same.