The number of attempted border crossings by people from Central America and Mexico has steadily increased since April 2020 and most single adults and families are being turned away, Homeland Security Secretary Alejandro Mayorkas said.
Poverty, violence and corruption in the Mexico and the Northern Triangle - Guatemala, Honduras and El Salvador - have led people to seek a better life in the United States for years, and there have been surges in the past.
Conditions in Mexico and the Northern Triangle - Guatemala, Honduras and El Salvador have continued to deteriorate and two hurricanes made living conditions even worse, while the coronavirus pandemic complicated the border situation.
US border agents conducted 100,441 apprehensions or expulsions of migrants at the border with Mexico in February, the U.S. Customs and Border Protection said last week, the highest monthly total since a border crisis of 2019.
The Biden government is creating a joint processing centre to transfer the children promptly into the custody of the Department of Health and Human Services (HHS) and is trying to find additional shelters for them.
President Joe Biden's administration has been struggling to speed up the processing of hundreds of youths under 18 who are crossing the southern border alone every day.
Biden urged migrants not to come to the United States on Tuesday, as criticism mounted over a surge in people arriving at the southern border with Mexico -- including thousands of unaccompanied children.