Migration: An Overview

More than 250 million people around the world live outside their country of origin, signifying a 49 percent increase in global migration since the start of the twenty-first century (Khullar and Chokshi 2019). As an umbrella term, the International Organization for Migration (IOM) of the United Nations describes migration as the act of moving away from one's usual place of residence, whether within a country or across international borders, temporarily or permanently, and for a variety of reasons (International Organization for Migration [IOM] n.d.). These reasons range from the voluntary pursuit of seasonal or long-term employment opportunities to involuntary relocations for safety and asylum. More specifically, individuals who move and resettle temporarily are classified as “migrants,” while those who resettle permanently in a new country are classified as “immigrants” (International Rescue Committee 2022). Throughout this chapter, the term “(im)migrants” is used when describing all individuals who migrate for any reason, over any distance and at any time or frequency.

The United States is home to approximately one-fifth of the world's (im)migrant population, accounting for 46.6 million individuals (Budiman 2020). Based on Pew Research Center data adjusted for undercount from US Census data, most (im)migrants in the United States have legal status: 45 percent or 20.7 million are naturalized citizens and 27 percent or 12.3 million are lawful permanent residents. Another quarter (23% or 10.5 million) are residents with unauthorized status (Budiman 2020). The United States has also accommodated more than three million refugees since Congress passed the Refugee Act of 1980, which established the current refugee program and sets standards for screening and admission (Connor et al. 2017; Khullar and Chokshi 2019). Despite their prominent presence in the United States, foreign-born residents are a minority population, constituting 14 percent of the United States population. For refugees in particular, the United Nations estimated that nearly one million refugees resided in the United States in 2019: approximately 0.2 percent of the country's population (United Nations Department of Economic and Social Affairs 2019).

Reasons for migration can be subdivided into macro-elements (independent of the individual), meso-elements (related to the individual but not under their control) and micro-elements (related to an individual's personal characteristics and attitudes) (Castelli 2018).