Latest on the crisis at the US border

Children are alternating schedules to make space for one another in confined facilities, some kids haven't seen sunlight in days, and others are taking turns showering, often going days without one.

That's the reality for the thousands of unaccompanied migrant children held up in US Border Patrol custody for days on end, according to case managers, attorneys and Border Patrol agents.

Bunk beds have been brought in to one of the processing facilities to help accommodate the influx of children. "Some of those are up to three bunks high," an agent told CNN, adding that children are also sleeping on plastic cots and mats on the floor and benches.

Customs and Border Protection is on pace to encounter more individuals on the border than in the last 20 years, Homeland Security Secretary Alejandro Mayorkas said Tuesday, adding that the agency is coming across children as young as six and seven years old.

More than 300 unaccompanied migrant children have been in Border Patrol custody for more than 10 days, CNN has learned. More than 4,200 minors are currently in custody, with an average time of 120 hours.

With an increasing number of children crossing the US-Mexico border alone, Border Patrol facilities are where kids have to stay until officials can transfer them to shelters that are appropriate for them. These facilities are designed to care for adults, not kids, and are akin to jail-like facilities with concrete walls and benches.

Children at stations in the Tucson, Arizona, region, for instance, have to be transported from Border Patrol stations to a central coordination center to get showers, the Border Patrol agent told CNN.

Federal law requires unaccompanied children to be turned over within 72 hours to the Department of Health and Human Services, which oversees a shelter network designed to house minors.

The senior official heading Customs and Border Protection, Troy Miller, told reporters that minors receive three meals daily, have 24/7 access to snacks and drinks and that showers are provided at least every 48 hours. They also have access to a recreation area, Miller said.

Read more here.

The statistics are staggering. More than 400,000 migrant children have crossed the US border without their parents since 2003.

And each time a new wave arrives, political controversy follows.

The numbers are on the rise again, with some children arriving who are as young as 6 or 7. This increase is sparking fierce debate in Washington, concern from children's advocates and an emergency response from the Biden administration.

Why have so many kids made this dangerous journey? And what happens to them once they reach the United States?

Here are some of the key things we know:

They're fleeing desperate conditions: There are many different reasons migrant children travel alone to the United States. CNN's years of reporting at the border and conversations with experts reveal a common thread: It's not a decision any family makes lightly.

Many of these children, who the government dubs "unaccompanied minors," make asylum claims when they arrive because they're fleeing persecution, gang violence and other forms of organized crime. Dire economic circumstances in their home countries may also contribute to their decisions to leave.

Many already have family members living in the United States: Children who cross the border alone are first held in Customs and Border Protection custody, then transferred to shelters run by the Department of Health and Human Services, where they're held until they're released to sponsors in the United States.

Changing policies are giving them a chance — for now:

So why are we seeing another surge of unaccompanied minors crossing the border now? There are many contributing factors at play in migrants' home countries -- and also a big change the Biden administration made.

Officials recently ended a controversial Trump administration policy that was put in place during the pandemic. That policy, which cited public health concerns, allowed the US government to kick out children who came to the border without giving them a chance to seek asylum. Critics said it flew in the face of international law and human rights norms, and endangered the lives of children seeking safety.

The Biden administration has stressed that the border isn't open, and officials have pledged to turn back most adults and families who cross. But Department of Homeland Security Secretary Alejandro Mayorkas says the cases of unaccompanied minors are different.

Read more here.

President Biden expanded on immigration policies his administration hopes to implement, attempting to draw a major distinction between his policies and that of the Trump administration, something the administration has been focused on as the number of migrants in custody at the border surges.

He added that many of the unaccompanied children come to the border with a phone number and his administration is working on setting up a system that would allow the US government to contact that number and determine, within seven days, if there is a safe and secure place for that child to go. 

CNN has reported that more than 300 unaccompanied migrant children have been in Border Patrol custody for more than 10 days, and that more than 4,200 minors are currently in custody, with an average time of 120 hours.

Biden also stressed that those seeking asylum should remain where they are as the administration works to set up the system of applying for asylum in place.

“We're in the process of getting set up, and it’s not going to take a whole long time, is to be able to apply for asylum in place, so don't leave your town or city or community. We're going to make sure we have facilities in those cities and towns run by DHS and also access with HHS, the health and human services to say, you can apply for asylum from where you are right now. Make your case. We'll have people there to determine whether or not you are able to meet the requirements and you qualify for asylum,” he said.