The personal is political; the political is grammatical
For some reason (*voice drips with irony*), I’ve been thinking a lot about immigration. Those thoughts are not related to grammar. But this blog is. So here’s my best attempt at staying on topic.
Migration, emigration or immigration?
Migration is the most general of the three terms; emigration and immigration both fall under its banner. Migrate means move from one area to another. It can relate to people, to animals or even to data and can be temporary or permanent. It doesn’t necessarily involve crossing a border – for example, people can migrate to a warmer part of the same country for winter, or they can migrate to a farming area every year to do seasonal work.
Emigration and immigration have a narrower definition. They describe different stages of the same thing: a person leaving his or her home country and settling permanently in a new one. Emigration is the leaving part; immigration is the settling part. (Note that this only applies to people and cannot take place within the same country.) So I would say:
My great-grandparents emigrated from Mexico. They immigrated to the United States.
Likewise, I would describe them as either emigrants or immigrants depending on the context. From a Mexican viewpoint, they were emigrants – people who left the country to settle elsewhere. From an American viewpoint, they were immigrants – people who came to the country from somewhere else.
One more thing. Like me, you probably hear the words immigration and immigrant far more often than emigration and emigrant. That’s because we live in a country that people generally want to enter en masse, not leave en masse. Not everyone is so lucky.