The number of immigrants detained by agencies of the Department of Homeland Security has been on the rise in the last decades. While in 1994, only an average of 6,785 people were in DHS custody on any given day, that number rose to more than 50,000 people in FY2019, almost doubling from approximately 28,000 in 2015 and surpassing the Trump administration goal of 45,000.
Immigrants who are in the United States illegally are typically arrested by Customs and Border Protection on the border or Immigration and Customs Enforcement in other parts of the country. The treatment of the increasing number of DHS detainees has been under scrutiny recently, with disease outbreaks and deaths in custody making headlines. Yet, the Trump administration has said it is planning to expand the number of detention beds and that it is planning to detain a daily average of 54,000 immigrants on a daily basis in FY2020. Detainee numbers are further driven up by not releasing asylum seekers and other detainees on bail until their hearings in immigration court, which has led to problems of overcrowding.
From 1990 to approximately 2005 more than a million illegal immigrants on the Southern border of the U.S. were not detained but simply driven back into Mexico every year, known as catch-and-release. Since the method fell out of favor, fewer and fewer people were turned around at the border (only around 100,000 people in 2017), in turn increasing the number of detainees.