In their article Can immigrants ever earn as much as native workers?Kathryn H. Anderson and Zhen Huang write that labor migration occurs for three reasons: work, family reunification, and refuge. Labor migrants fill market needs in the host country, and their success and assimilation contribute to local economic development. Refugees are admitted for humanitarian reasons, and their acceptance into a country indicates a willingness to help those most in need. Finally, family reunification fulfills another humanitarian goal, which is to keep families intact and children and elderly parents protected.
There are also two types of labor migration: permanent or temporary. Temporary migrants are often undocumented or brought into the country to fill specific labor market needs. Permanent migrants have an incentive to invest in skills that are valued in the host labor market. This investment benefits them and across generations as immigrants become more similar to natives in their skills and behavior.
Temporary immigrants, however, have less incentive to invest in local skills and culture. Their time in the host country is more uncertain, and these investments are less likely to result in higher incomes and better jobs. Labor migrants and refugees who do not assimilate are often marginalized or confined to ethnic enclaves and this separation lessens social interaction within a country. In the extreme, it generates social unrest and resentment between groups.
Policies that facilitate assimilation in the labor market for immigrants can increase labor productivity, domestic output, and social cohesion. Immigrants who are self-sufficient pay local taxes and need fewer public resources for the maintenance of their families; their children benefit as well, and are afforded more opportunities to move up the economic ladder. It is therefore economically and socially beneficial for the host country that immigrants assimilate and integrate with society.