"Numerous Members of the 115th Congress have demonstrated interest in the global migration crisis, particularly as a result of the recent flows of migrants and refugees to the United States from Central America and Mexico. In 2017, an estimated 232 million international migrants formed roughly 3% of the world's population. The International Organization for Migration (IOM) defines a migrant as 'any individual who has temporarily or permanently crossed an international border and is no longer residing in his/her country of origin/habitual residence.' The decision to move is usually made out of a choice related to livelihood, improved economic circumstances, or family ties. However, as discussed below, certain factors may force individuals to leave involuntarily."
CRS In Focus, IF11003
Congressional Research Service: https://crsreports.congress.gov/