APHUG Unit 2 Key Terms

Age-Sex distribution

Model used in population geography that describes the ages and numbers of males and females within a given population; also called a population pyramid.

Agricultural density

The number of farmers per unit area of farmland. 

Arithmetic density

The number of people living in a given unit area. 

Baby Boom

A cohort of individuals born in the United States between 1946 and 1964, which was just after World War II in a time of relative peace and prosperity. These conditions allowed for better education and job opportunities, encouraging high rates of both marriage and fertility. 

Baby Bust

Period during the 1960s and 1970s when fertility rates in the United States dropped as large numbers of women from the baby boom generation sought higher levels of education and more competitive jobs, causing them to marry later in life. As such, the fertility rate dropped considerably, in contrast to the baby boom, in which fertility rates were quite high.

Carrying capacity

The largest number of people that the environment of a particular area can sustainably support. 

Chain migration

The migration event in which individuals follow the migratory path of preceding friends or family members to an existing community. 

Child mortality rate

Number of deaths per thousand children within the first five years of life. 

Cohort

A population group unified by a specific common characteristic, such as age, and subsequently treated as a statistical unit. 

Cotton Belt

The term by which the American South used to be known, as cotton historically dominated the agricultural economy of the region. The same area is now known as the New South or Sun Belt because people have migrated here from older cities in the industrial north for a better climate and new job opportunities. 

Crude birth rate

The number of live births per year per thousand people. 

Crude death rate

The number of deaths per year per thousand people.

Demographic transition model

A sequence of demographic changes in which a country moves from high birth and death rates to low birth and death rates through time.

Demography

The study of human populations, including their temporal and ­spatial dynamics.

Dependency ratio

The ratio of the number of people who are either too old or too young to provide for themselves to the number of people who must support them through their own labor. This is usually expressed in the form n:100, where n equals the number of dependents.

Doubling time

Time period required for a population experiencing exponential growth to double in size completely.

Emigration

The process of moving out of a particular country, usually the individual person’s country of origin. 

Epidemiological transition

Sudden population growth as a result of improved food security and health care, followed by a plateau in growth because of subsequent declines in fertility rates. 

Exponential growth

Growth that occurs when a fixed percentage of new people is added to a population each year. Exponential growth is compound because the fixed growth rate applies to an ever-increasing population.

Forced migration

The migration event in which individuals are forced to leave a country against their will.

Generation X

A term coined by artist and author Douglas Coupland to describe people born in the United States between the years 1965 and 1980. This post-baby-boom generation will have to support the baby boom cohort as they head into their retirement years.

Ecumene

The portion of Earth’s surface occupied by permanent human settlement.

Natural Increase Rate (NIR)

Percentage by which a population grows in a year (CBR - CDR)

Total Fertility Rate (TFR)

Average number of children a woman will have in her lifetime.

Infant Mortality Rate (IMR)

Deaths of infants under 1 year per 1,000 live births.

Migration

Permanent move to a new location.

Immigration

Moving into a new country.

Push Factor

Reason people leave an area (e.g., war, famine).

Pull Factor

Reason people move to a new area (e.g., jobs, safety)

Refugee

Someone fleeing conflict or persecution.

Internally Displaced Person (IDP)

Displaced within their own country.

Step Migration

Migration to a distant destination that occurs in stages

Brain Drain

Emigration of highly skilled workers.

Malthusian Theory

A theory by Thomas Malthus stating that population grows faster than food supply, which will lead to famine, disease, and conflict unless controlled by moral restraint or natural disasters.