Population and Migration Patterns and Processes

Age-sex distribution

A 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 Il 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 accounting equation

An equation that summarizes the amount of growth or decline in a population within a country during a particular time period, taking into account both natural increase and net migration.

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.

Immigration

The process of individuals moving into a new country with the intention of remaining there.

Infant mortality rate

The percentage of children who die before their first birthday within a particular area or country.

Internal migration

The permanent or semipermanent movement of individuals within a particular country.

Intervening obstacles

Any forces or factors that may limit human migration.

Life expectancy

The average age individuals are expected to live, which varies across space, between genders, and even between races.

Thomas Malthus

Author of Essay on the Principle of Population (1798) who claimed that population grows at an exponential rate while food production increases arithmetically, and thereby that, eventually, population growth would outpace food production.

Maternal mortality rate

Number of deaths per thousand of women giving birth.

Migration

A long-term move of a person from one political jurisdiction to another.

Natural increase rate

The difference between the number of births and number of deaths within a particular country.

Neo-Malthusian

Advocacy of population-control programs to ensure enough resources for current and future populations.

Overpopulation

A value judgment based on the notion that the resources of a particular area are not great enough to support that area's current population.

Physiologic density

A ratio of human population to the area of cropland, used in less-developed countries dominated by subsistence agriculture.

Population density

A measurement of the number of persons per unit of land area.

Population geography

A division of human geography concerned with spatial variations in distribution, composition, growth, and movements of population.

Population pyramid

A model used in population geography to show the age and sex distribution of a particular population.

Pull factors

Attractions that draw migrants to a certain place, such as a pleasant climate and employment or educational opportunities.

Push factors

Incentives for potential migrants to leave a place, such as a harsh climate, economic reces-sion, or political turmoil.

Refugees

People who leave their home because they are forced out, but not because they are being officially relocated or enslaved.

Rust belt

The northern industrial states of the United States, including Ohio, Michigan, and Pennsylvania, in which heavy industry was once the dominant economic activity. In the 1960s, 1970s, and 1980s, these states lost much of their economic base to economically attractive regions of the United States and to countries where labor was cheaper, leaving old machinery to rust in the moist northern climate.

Sun belt

US region, mostly comprising southeastern and southwestern states, which has grown most dramatically since World War II.

Total fertility rate

The average number of children born to a woman during her childbearing years.

Voluntary migration

Movement of an individual who consciously and voluntarily decides to locate to a new area —the opposite of forced migration.

Zero population growth

Proposal to end population growth through a variety of official and nongovernmental family-planning programs.