There are many economic, social and physical reasons why people emigrate, and they can usually be classified into push and pull factors. Push factors are those associated with the area of origin, while pull factors are those that are associated with the area of destination.
The dominant motive for migration is economic, and pull factors tend to be higher wages and greater demand for labour perhaps found in centres of industry and commerce. Economic push factors can include overpopulation and the absence of economic opportunity. Social and physical reasons tend to involve forced migration, and an example of a social push factor would be intolerance towards a certain cultural group, such as the fleeing of Jewish refugees from Nazi Germany in the 1930s. An example of a physical push factor would be a natural disaster, such as the East African drought of 2011. Let’s look at these push and pull factors in more detail.
Economic motives loom large in all human movements, but are particularly important with regards to migration. Better economic opportunities, more jobs, and the promise of a better life often pull people towards a new country. Sometimes this is encouraged by the destination country, such as the employment campaign in the Caribbean by London bus companies in the 1960s, which actively recruited young men to move to London to work as bus drivers, often followed by their families. Another example might be the ‘brain drain’ to America that occurred in the latter half of the 20th Century from several other Western nations.
Economic push factors tend to be the exact reversal of the pull factors; a lack of economic opportunity and jobs tend to push people to look out of their area of origin for their futures. An example of this is the migration of Mexicans and people from other Central American countries into the United States of America, where they often work low-wage, long-hour jobs in farming, construction and domestic labour. It is difficult to classify this case purely with push factors however, as often the factors associated with the country of origin are just as important as the factors associated with the country of destination.
Forced migration has also been used for economic gain, such as the 20 million men, women and children who were forcibly carried as slaves to the Americas between the 16th and 18th Centuries.
Sometimes there are social pull factors in migration, for example the principles of religious tolerance that the United States of America was founded on, which attracted religious refugees such as the Mennonites, who settled in Pennsylvania, but more often migration caused by social factors is a push, such as active religious persecution, as it was in the case of the Huguenots in 16th Century France, the Puritans in 17th England, and the Jewish refugees from Nazi Germany.
Under physical factors we are not including things like the promise of fertile lands that prompted the Westward migration across the United States in the 19th Century, more the physical factors that have compelled people to seek safety elsewhere. A prime example would be the mass exodus from the island of Montserrat leading up to the eruption of the La Soufriere Hills volcano in 1995, which led to two thirds of the population abandoning the island. (N.B. do not confuse the La Soufriere Hills volcano on Montserrat with La Soufriere on the island of Saint Vincent, or La Grande Soufriere on the island of Basse-Terre)