Over 171,000 migrants were apprehended at the US border in March, the highest number in 15 years

• A record number of migrants were taken into CBP custody last month, new data shows.
• Over 171,000 migrants were apprehended at the US-Mexico border in March.
• In January, the number taken into custody stood at 78,442.

Over 171,000 migrants were apprehended at the US-Mexico border in March, according to a Washington Post analysis of preliminary data from Customs and Border Protection (CBP).

This marks the highest number of migrants taken into custody in a single month since 2006. In January, the number taken into custody stood at 78,442.

The massive uptick comes as the Biden administration is under increasing scrutiny over the situation at the border, particularly as it pertains to unaccompanied migrant children.

President Joe Biden has faced criticism over holding migrant children in jail-like facilities meant for adults over the legal limit of 72 hours, when they're meant to be transferred from CBP to the custody of Health and Human Services. But the COVID-19 pandemic has presented challenges in this regarding, leading to limited space as officials seek to uphold public health guidelines.

The Post reports that CBP took in over 18,800 unaccompanied minors in March, marking a 99% increase from February. The previous one-month high comes from May 2019 and is far lower: 11,861 minors.

There are a lot of complicated factors contributing to the situation at the border.

There is generally an uptick in migrant arrivals around spring, when the weather gets warmer, before it levels off around May. The COVID-19 pandemic also created a backlog as people waited to make the journey north. Devastating hurricanes in November that hit the Northern Triangle countries in Central America that many migrants come from - El Salvador, Honduras, and Guatemala - have also played a role.

Meanwhile, congressional Republicans have blamed Biden's more welcoming messaging on immigration and his plan to provide a pathway to citizenship for over 11 million undocumented immigrants for the massive increase in arrivals. They've referred to the situation as a "Biden border crisis," a characterization the White House has vehemently rejected.

That said, Department of Homeland Security Secretary Alejandro Mayorkas recently acknowledged that the number of arrivals was reaching historic levels. In a statement last month, he said, "We are on pace to encounter more individuals on the southwest border than we have in the last 20 years."

Democrats, especially progressive-leaning lawmakers, have been critical of the conditions children are being held in and pressured Biden to resolve the situation quickly.

Biden tapped FEMA to help with the situation, as his administration continues to urge migrants not to make the journey up to the border.