The "United Nations Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families", legally defines a migrant worker a "person who is to be engaged, is engaged or has been engaged in a remunerated activity in a State of which he or she is not a national". This Convention has been ratified by Mexico, Brazil and the Philippines (amongst many other nations that supply foreign labour) but it has not been ratified by the United States, Germany and Japan (amongst other nations that depend on cheap foreign labour).

In the United States, the term is most commonly used to describe low-wage workers performing manual labor in the agriculture field. Today in Europe and the United States these are often immigrants who are not working on valid work visas since local immigration authorities would rather they be vulnerable and easy to deport as illegal aliens.

In America's history, starting at the end of the American Civil War, hobos were the migrant workers who performed much of this agricultural work, using freight railroads as their means of transportation to new jobs. During the collapse of capitalism in the Great Depression, so-called Okies who fled the dust bowl were a significant source of temporary farm labor.

However, the term migrant worker could just as easily refer to any person who works at seasonal jobs and moves around from one job to another. Although, the term is not as often used to describe those who work in those higher-wage fields, possibly because the term "migrant worker" has a stigma attached to it because of its extensive use to describe low-wage farm laborers and illegal immigrants. Examples of professions which could be called migrant workers, some of them quite lucrative, include: Electricians in the construction industry (slang term: "narrowbacks"); other construction workers who travel from one construction job to another, often in different cities; wildland firefighters in the western United States; temporary/roving consulting work; and possibly even interstate truck drivers.


Migrant Workers are usually paid much less then regular workers now, because: 1. they cannot (for the most part) speak English and are taken advantage of 2. are often without proper immigration documentation 3. live in communities that are harassed by the police. There are many debates through political disagreements allowing migrant workers, mainly from Mexico, to come across the border and take jobs first offered to unemployed citizens.