"In FY2014, the number of unaccompanied alien children (UAC, unaccompanied children) that were apprehended at the Southwest border while attempting to enter the United States without authorization reached a peak, straining the system put in place over the past decade to handle such cases. Prior to FY2014, UAC apprehensions were steadily increasing. For example, in FY2011, the U.S. Border Patrol (USBP) apprehended 16,067 unaccompanied children at the Southwest border, whereas in FY2014 more than 68,500 unaccompanied children were apprehended. In FY2015, UAC apprehensions declined 42% to 39,970. At the close of FY2016 they increased to 59,692, roughly 20,000 more than in FY2015, and 9,000 less than the peak of FY2014. During the first two months of FY2017 (October and November, 2016), USBP apprehended 14,128 unaccompanied children. Apprehensions in the first two months of FY2015 and FY2016 were 5,143 and 10,588, respectively. UAC are defined in statute as children who lack lawful immigration status in the United States, who are under the age of 18, and who either are without a parent or legal guardian in the United States or without a parent or legal guardian in the United States who is available to provide care and physical custody. Two statutes and a legal settlement directly affect U.S. policy for the treatment and administrative processing of UAC: the Trafficking Victims Protection Reauthorization Act of 2008 (P.L. 110-457); the Homeland Security Act of 2002 (P.L. 107-296); and the 'Flores Settlement Agreement' of 1997."
CRS Report for Congress, R43599
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html