The picture of migration, in the US and worldwide, is vastly more complicated than at first glance -- and modern technology, economic and ecological factors, and ease of movement promise greater complexity in the future. While much of the focus is given to the influx of immigrants into the richer Northern countries like the US from the developing nations of the global South, the true picture of migration shows a dense web of movement: migrants moving back and forth between their home country and their adopted country; agricultural workers moving within one country, sometimes several times a year to follow the seasonal changes in work opportunities; new immigrants who are willing and able to keep pressing on to new locations in search of better opportunity or more stable conditions elsewhere.
This complex picture of modern human migration is a result of improved transportation and communication, increasing social inequality, a changing climate, a growing world economy, and greater ease of movement across the globe. Rapid dissemination of information, updating far-off communities on the opportunities of a different community, has fueled population movement further. As these factors have accelerated and reached more corners of the globe, migration in the US and globally has changed. Migrants have begun working in industries and communities that until recently did not largely rely on migrant workers, like salmon fisheries in Alaska, or industrial dairy farms in Wisconsin. The new migrants often do not have experience in the field where they have found work; the employers in these communities are often not equipped to communicate the health risks associated with the work they are offering, in a linguistically and culturally appropriate way. The changes and increases in migration patterns, the arrival of migrants into new communities, and the participation in new and often dangerous forms of employment have therefore strong effects on the health, health risks, and health management of mobile populations.