A record 3,200 unaccompanied migrant children are being held along the US-Mexico border according to new reports; a figure said to have tripled over the past two weeks.

About 1,400 minors have been held past the legal limit of 72 hours, after which they are required to be transferred to government-sponsored shelters (see an overview of the process). Those shelters are now reaching bed limits, having already removed a 50% capacity rule designed to limit the spread of COVID-19.

The estimates come amid a broader monthslong surge of migrants—mostly single adults—along the southwest border, with encounters averaging around 74,000 per month since October (see data). It marks the highest level during the same time period in at least eight years, but is less than a 2019 summer surge that exceeded 100,000 encounters per month.

Some critics blame softer border policy by the Biden administration for the surge. Others argue the White House has largely kept the previous administration’s “Remain in Mexico” policy intact, while being more accommodating with unaccompanied children.