Kposowa2019MigrationConcepts.pdf

Demography:
- Etymology: Greek words 'demos' (people) and 'graphé' (writings)
- Defined as the systematic study of human populations, their size, composition, and changes over time.
- Focus on clearly defined spatial units (countries, states, counties, etc.) to analyze population characteristics, particularly age and sex distribution
Components of Population Change:
- Fertility: Population growth through birth.
- Mortality: Population decline through death.
- Migration: Movement between populations affecting both origin and destination locations
- Natural increase is calculated using the formula: (B - D)
- Where B is births and D is deaths.

Migration:
- Requires permanent change in residence lasting at least one year
- Excludes short-distance commutes, temporary changes, and vacation moves
- Must involve crossing an administrative boundary, typically a county line in the U.S.

Describes the flows of migrants from origins to destinations, denoted as M_1
- Typically, flows occur in both directions (e.g., from Los Angeles to New York and vice versa)

Internal Migration:
- Movement within a country where individuals can be categorized as both out-migrants (leaving) and in-migrants (arriving).
Net Migration:
- Difference between in-migrants and out-migrants. Formula: M{in} - M{out}
- Negative indicates loss of population
- Positive indicates gain of population
Gross Migration:
- Sum of in-migrants and out-migrants: M{in} + M{out}
- Indicates the volume of movement, regardless of direction

Migration Efficiency:
- Ability of an area to attract migrants. Calculated as: ext{Net Migration} / ext{Gross Migration}
- Positive values indicate efficiency; negative values indicate inefficiency
Area Holding Power:
- The ability of an area to retain its population. High holding power implies a significant portion of the population was born and remains in that area.

International Migration:
- Involves crossing an international boundary. A migrant must reside for a year in the new country
Internally Displaced Persons:
- Individuals forced to flee within their home country due to war or disasters

Nativity Status:
- Native-born: Those born in the U.S. or U.S. territories
- Foreign-born: Individuals born abroad or not a U.S. citizen at birth
Legal Immigrants:
- Individuals allowed to stay permanently after obtaining a visa
Illegal Immigrants:
- Individuals entering a country without legal authorization or overstaying visas

Presumption of Permanence:
- U.S. immigration policy presumes that foreigners intend to stay permanently unless proven otherwise
- Nonimmigrant visas for temporary stays; immigrants must demonstrate intentions to return home.
Nonimmigrant Population:
- Includes tourists, business travelers, and students.
- Their presence is vital for U.S. economy and demographics

Population change may be modeled with: P{t} = P{t-1} + B - D + I - O
- Where I is immigration and O is emigration

Early Regulation:
- Initiated with the Immigration Act of 1891, establishing the Office of Immigration
- The role has evolved considerably with changing laws and administrative bodies over the decades.