What is the Caravan and what should U.S. immigration authorities do with it?

What is the Caravan and what should U.S. immigration authorities do with it? We have heard a lot about the “Caravan” of immigrants making its way north through Mexico from the Northern Triangle- El Salvador, Honduras and Guatemala- of Central America.  Once numbering over 1200 people, the remaining 150-200 members Caravan arrived at the U.S. border to request refuge in the United States.   When they got there, they were told that the U.S. was full.  There was not even a manger to house them.