On the campaign trail, Joe Biden made sweeping promises to reform US immigration, vowing to "take urgent action" and undo the policies of Donald Trump.
And since taking office, the Democrat has ordered the reunification of migrant children with their families, ended construction of the border wall and called for reviews of legal immigration programmes terminated by his predecessor.
He has also presided over an influx of arrivals to the US southern border, including hundreds of unaccompanied children who are being held in US immigration detention facilities.
Here's a look at what Mr Biden has - and hasn't - done so far, and how it differs from Mr Trump.
Is there a surge at the border?
Numbers of arriving migrants are definitely rising.
A growing influx of migrants has led to a record number of children - 3,200 - being held in US immigration facilities as of 8 March.
US media reported that the figure had trebled in the past two weeks alone. It was also reported that half of the children are being held beyond the legal three-day limit, after which they must be transferred to the custody of health officials.
In January, the month that Mr Biden took office, 5,871 unaccompanied children crossed the border - up from 4,995 in December - according to data from US Customs and Border Protection (CPB).
And CPB reported an average of nearly 3,000 arrests per day in January, the last month from which data is available, compared with an average of about 1,800 arrests in January 2020.
Data for February is not yet available, but CBS News reported that at least 7,000 migrant children entered the US that month.
The Biden administration has disputed that there is yet a "crisis" at the border. Secretary of Homeland Security Alejandro Mayorkas told a reporter last week that it was "overwhelming" but not a crisis.
This year's uptick is still modest compared with 2019, when border officials apprehended more than 76,000 unaccompanied minors.
But pressure is building at the southern border, and some reports suggest the numbers are on pace to overtake the record highs of that year.
Behind closed doors, Mr Mayorkas's comments suggest he might agree. He told senior officials last month to "prepare for border surges now" according to emails obtained by the Washington Times.
And last week Russell Hott, a senior official with Immigration and Customs Enforcement (Ice) told staff in an email that arrivals of unaccompanied minors and families at the US border this year is expected to be the "the highest numbers observed in over 20 years," according to the Washington Post newspaper.
How are migrants entering the US?
Migrants cross the border in one of two ways.
Those who "have suffered persecution or fear that they will suffer persecution" in their home country are eligible for asylum when they present themselves at a port of entry for admission into the US.
Others may evade immigration inspectors and border patrol by hiding in vehicles or travelling undetected across unprotected - and typically treacherous - sections of the US-Mexico border.
According to the Pew Research Center, at least 40% of unauthorised migrants in the country entered legally on short-term visas and overstayed.
Are unaccompanied children being held?
While in office, Donald Trump faced outrage over the conditions inside border facilities holding minors. Images from inside the detention centres showed children overcrowded in metal cages, others sleeping under foil blankets.
Some of these Trump-era facilities - now renovated and upgraded - are being used again.
Mr Biden has so far left a Trump-era Covid-19 emergency policy in place, which allows US authorities to expel almost all undocumented migrants seeking entry - bypassing normal immigration laws and protections.
But unlike Mr Trump, Mr Biden has decided not to refuse entry to migrant children or teenagers.
Now, hundreds of migrant children are crossing the border each day, and thousands of minors have been detained in holding facilities at the country's southwest border in recent weeks.
Despite concerns about coronavirus, health officials the Centers for Disease Control and Prevention (CDC) have said these facilities can open at 100% capacity.
The children start out being held by the Department of Homeland Security (DHS) for a maximum of 72 hours.
They are then turned over to the Department of Health and Human Services (HHS) "to address the needs of that child", Secretary Mayorkas said, including vetting the sponsor families who will house the children while their cases are adjudicated in immigration court.
Children and teens are held by HHS for a month on average, he said.
How is Biden defending that?
Human rights groups and members of Mr Biden's own party have criticised the decision to hold children in government custody for the weeks or months it takes to match them with sponsors.
Some of Mr Biden's critics have suggested the process harkens back to Trump-era policy, the major change being that children are held for less time under President Biden.
Mr Mayorkas dismissed a comparison to Mr Trump's immigration programs as "absolutely inaccurate", saying his department was acting in the "best interest" of the migrant children.
But some advocates say that with most children arriving with plans to reunite with sponsors - typically friends or family - they should be transferred immediately to their care.
And according to preliminary plans obtained by US media, such a system may already be in the works.
The Biden administration is reportedly rushing to convert its existing facilities into "reception centres", meant to rapidly process migrant families with the goal of releasing them into the US within 72 hours of arrival.
The proposal would
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