They're children. Tens of thousands of them, boys and girls, some just toddlers, many under 12 years old, who somehow made it here from the violent, gang-ridden countries of Honduras, Guatemala and El Salvador.
Gradually packing detention facilities along the Mexican border, their numbers finally reached a point that all of America not only has noticed but also can hardly talk about anything else.
There are predictably partisan arguments about why this is happening, whom to blame and what to do about it. Here's the bottom line.
The children have arrived claiming to be refugees, and for more than half a century, international law and our own has governed the treatment of refugees seeking asylum. Many lack proof that their lives were in danger and will have to be sent back. But every one of them must receive due process and deserves to be treated humanely while in U.S. custody.
Conservatives say that just flying the children home would be 99 percent cheaper than President Obama's $3.7 billion plan to deal with them. U.S. Rep. Zoe Lofgren, D-San Jose, an expert on immigration issues, argues they miss a crucial point.
First the U.S. needs to determine whether the children have legitimate claims of asylum due to violence or trafficking. Honduras has the highest homicide rate of any country in the world, and organized crime and gang violence is soaring in El Salvador and Guatemala.
The notion that Obama rolled out a welcome mat for the children is preposterous. He has earned the title deporter-in-chief, expelling record numbers of immigrants.
And the controversy over the 2008 law signed by George W. Bush to help victims of trafficking is a straw dog.
The law was supposed to ensure that children fleeing persecution and trafficking or other severe abuse were not returned to grave danger. That's not the problem. The problem is too few immigration judges to deal with a backlog of more than 375,000 cases, including the latest flood of 50,000 children.
Republicans want to fund patrols but not judges. There are just 243 nationwide. Los Angeles County, by comparison, has more than 400 on its Superior Court.
Obama's request for $3.7 billion to deal with the crisis is a good start. It includes $64 million for more judges and $1.8 billion for better living conditions while kids await hearings.
Obama also wants $300 million to improve living conditions in Central America, but that has to be part of a regional strategy.
The United States has been distracted by the wars in the Middle East and ignored the crisis close to home. A multi-nation approach like the one that restored order in Colombia could work again.
Refugees from violence are a worldwide challenge. People fleeing places like Somalia, Syria and Uganda often end up in nearby countries that are ill-equipped for the influx. But they try.
Surely, the United States will meet this hemisphere's crisis in a manner befitting our history.