In Photos: Immigration to the United States

A man returns to the Mexican bank of the Rio Grande after washing his horse in the river near Mission, Texas, in 2014. The Rio Grande valley was the center of an immigration crisis, as more people were crossing illegally from Mexico into that sector than any other stretch of the 1,933-mile US border

Undocumented immigrant families are spotted by a helicopter before being taken into custody by US Border Patrol agents near McAllen, Texas, in 2014. Gov Rick Perry had announced that he would send 1,000 national guard troops to help stem the flow of immigrants

An instructor yells at a trainee upon her arrival with fellow agents at the US Border Patrol Academy in Artesia, New Mexico, in 2017. All new agents must complete a month-long training course before assuming their posts along the border. President Trump has pledged to add an additional 5,000 agents to the force of more than 21,000 as part of his border security policy