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===Explanator models: The Push Pull Theory===

===Explanator models: The Push Pull Theory===

According to Ravenstein’s push-pull theory, adverse factors at home can "push" people out, making them want to emigrate.  Attractive factors abroad can "pull" people in.  The model is not deterministic—many more people think about migrating than actually do so, and chance and luck plays large roles.

According to Ravenstein's push-pull theory, adverse factors at home can "push" people out, making them want to emigrate.  Attractive factors abroad can "pull" people in.  The model is not deterministic—many more people think about migrating than actually do so, and chance and luck plays large roles.

   

   

The most important push factor is difficulty in making a good living at home.  In an agricultural society, there may be a shortage of land and a surplus of workers, so that over time either the farms become smaller, or the excess population leaves agriculture.  In an urban society if there is stagnation in industry, unemployment results unless people leave.  In any given place, some people will be strongly rooted and others will be more eager to move on.  For example, eldest sons who are in line to inherit the family farm would be more rooted than younger sons with poor prospects of ever owning land.  Workers unhappy with their jobs or pessimistic about future prospects would be more willing to consider a move to improve their possibilities.  

The most important push factor is difficulty in making a good living at home.  In an agricultural society, there may be a shortage of land and a surplus of workers, so that over time either the farms become smaller, or the excess population leaves agriculture.  In an urban society if there is stagnation in industry, unemployment results unless people leave.  In any given place, some people will be strongly rooted and others will be more eager to move on.  For example, eldest sons who are in line to inherit the family farm would be more rooted than younger sons with poor prospects of ever owning land.  Workers unhappy with their jobs or pessimistic about future prospects would be more willing to consider a move to improve their possibilities.  

===Selectivity===

===Selectivity===

The people most likely to migrate are young adults, especially young men.  People with more assets (such as cash or education or adventurous personality) would be more likely to leave.  Looked at the other way, people who want to leave for one reason or another will try to save money, get more skills or schooling, and avoid long-term commitments.  In practice, most migration is “chained.”  People follow a chain of kinfolk who have already settled in a new area, and who provide information, money and encouragement for others to follow. (Of course, they can also warn that conditions are poor, and don’t come right now.)

The people most likely to migrate are young adults, especially young men.  People with more assets (such as cash or education or adventurous personality) would be more likely to leave.  Looked at the other way, people who want to leave for one reason or another will try to save money, get more skills or schooling, and avoid long-term commitments.  In practice, most migration is “chained.”  People follow a chain of kinfolk who have already settled in a new area, and who provide information, money and encouragement for others to follow. (Of course, they can also warn that conditions are poor, and don't come right now.)

A person has to be old enough to be independent of the family to make the decision to migrate. A century ago people aged 15 to 20 were full-time workers and could make independent decisions themselves. Today, academic credentials are much more important, and migration decisions usually come after people finish high school or college. Today in the US, migration peaks for young adults in their twenties. By the late thirties they have usually settled down, geographically.

A person has to be old enough to be independent of the family to make the decision to migrate. A century ago people aged 15 to 20 were full-time workers and could make independent decisions themselves. Today, academic credentials are much more important, and migration decisions usually come after people finish high school or college. Today in the US, migration peaks for young adults in their twenties. By the late thirties they have usually settled down, geographically.

The chief sending and receiving countries change every decade, though the USA is usually the largest recipient. By 2000 the largest donor countries were China, Mexico and India.  

The chief sending and receiving countries change every decade, though the USA is usually the largest recipient. By 2000 the largest donor countries were China, Mexico and India.  

===Impact===

===Impact===

The impact of immigration on the donor countries is modest.  Things don’t happen; emigration reduces the available workforce, and thereby tends to raise wages. The '''Brain Drain''' effect, however, keeps the level of technology and complexity lower than it would otherwise have been. Remittances from the emigrants can be a major factor in very poor countries, such as Haiti. Mexico receives over $2 billion a year from emigrants. This money is mostly spent on consumer goods; it has a "multiplier" effect that makes the whole community better off, not just the relatives who receive the money.  

The impact of immigration on the donor countries is modest.  Things don't happen; emigration reduces the available workforce, and thereby tends to raise wages. The '''Brain Drain''' effect, however, keeps the level of technology and complexity lower than it would otherwise have been. Remittances from the emigrants can be a major factor in very poor countries, such as Haiti. Mexico receives over $2 billion a year from emigrants. This money is mostly spent on consumer goods; it has a "multiplier" effect that makes the whole community better off, not just the relatives who receive the money.  

The largest host destinations in 2000 were: USA, Germany, and Canada.

The largest host destinations in 2000 were: USA, Germany, and Canada.

Millions of Germans emigrated (especially to the US) in the 19th century. It became an importer after World War Two, and again after the Cold War ended in 1989, of millions of German political refugees from Eastern Europe. As the West German economy boomed, it brought in some 19 million Turkish, Slavic and Italian guest workers ("Gastarbeiter"). Five million of these "guests" brought their families and stayed permanently, but they are not accorded full citizenship status.  

Millions of Germans emigrated (especially to the US) in the 19th century. It became an importer after World War Two, and again after the Cold War ended in 1989, of millions of German political refugees from Eastern Europe. As the West German economy boomed, it brought in some 19 million Turkish, Slavic and Italian guest workers ("Gastarbeiter"). Five million of these "guests" brought their families and stayed permanently, but they are not accorded full citizenship status.  

Puerto Rico, became part of the USA in 1898, and the residents gained full citizenship status in 1917. Millions emigrated from the poor island to the much richer mainland, especially New York City and environs. Recently, immigrants from Cuba and the Dominican Republic migrated to Puerto Rico, attracted by higher wages and the island’s Spanish language and culture.

Puerto Rico, became part of the USA in 1898, and the residents gained full citizenship status in 1917. Millions emigrated from the poor island to the much richer mainland, especially New York City and environs. Recently, immigrants from Cuba and the Dominican Republic migrated to Puerto Rico, attracted by higher wages and the island's Spanish language and culture.

The USA has primarily been a destination for immigrants. Most of the emigration out of the USA has been of immigrants who stayed for a while then returned home.  However, there has been a small flow to Canada.

The USA has primarily been a destination for immigrants. Most of the emigration out of the USA has been of immigrants who stayed for a while then returned home.  However, there has been a small flow to Canada.