Trump's immigration legacy: A border wall Biden vows to freeze

This story is part of "America in Transition," a series of reports on key parts of Donald Trump's legacy, Joe Biden's plans for change, and what's at stake in 2021. It airs Tuesday nights on ABC News Live Prime at 7 p.m. ET.

Even in the twilight of the Trump administration, Nayda Alvarez is battling to keep construction of the border wall out of her south Texas backyard.

"They make it seem that there is an invasion," said Alvarez, whose property sits along the Rio Grande, looking into Mexico. "It's just been an over-exaggerated lie."

Several landowners along the southern U.S. border have been fighting the government in court as it seeks to seize parts of their property through eminent domain and erect barriers just feet from their homes. Many insist they have not seen the illegal crossings or other activity the wall is meant to prevent.

"If I would see immigrants crossing like crazy, my grandkids wouldn't go outside and play. I'd probably move here for my own safety," said Alvarez. She painted the slogan "no border wall" on the roof of her house to make clear that she wants it all to stop.

"There's no crisis, no national emergency. The national emergency that we have right now is a pandemic," she said.

As President Donald Trump prepares to leave office, the border wall remains a divisive symbol of his immigration legacy that won't be easily undone, even as President-elect Joe Biden vows to freeze construction and overhaul enforcement policies.

American taxpayers are on the hook for at least $10 billion in contracts awarded over the last three years, according to an analysis by ProPublica and Texas Tribune. Despite Trump's repeated promises, Mexico has not paid one cent. More than 400 miles of barrier has been newly built or reconstructed so far, according to Department of Homeland Security data.

"It's been a game changer," said outgoing Customs and Border Protection Commissioner Mark Morgan. "It's much more than steel and concrete going in the ground. It has lighting, access roads and integrated technology. Again, that's part of that multilayered strategy."

Border officials say illegal crossings have slowed to a relative trickle in recent months thanks to COVID-19, the economic recession and Trump's wall.

Morgan says the flow of families from Northern Triangle countries in Central America, which precipitated a humanitarian crisis along the southern border in 2018, is down by 75% from the peak.

"The critics now say they want to undo all of it. If you do that, mark my words, you're going to -- last year's crisis is going to look like child's play with respect to what's going to happen," Morgan said.

Biden has said he'll move to freeze new border wall construction, ending Trump's national emergency declaration and stopping use of Pentagon funds to pay for it. He also plans to begin reversing a wave of administrative regulations Trump imposed to limit legal immigration to the U.S.

The incoming administration promises to resume acceptance of tens of thousands of displaced refugees, lifting the annual cap from just 15,000 in 2020 to 125,000 next year. Biden has also pledged to reopen the borders to asylum seekers who are now turned away to wait in other countries.

"People have been [living in] increasingly destitute situations. They've been victims of violence from the cartels," said Ali Noorani, president and CEO of the National Immigration Forum, a nonpartisan advocacy group. "Right now, our asylum system pretty much does not exist."

And while the Trump administration ended its controversial child separation policy in 2018, the human toll of those more than 4,000 family breakups is still being felt.

An estimated 545 children taken from their parents have not yet been reunited, according to the American Civil Liberties Union.

"It's pretty shocking that 2 1/2 years later, after this policy was stopped, that the government is still handing over information and we're still searching for some of these families," said Cathleen Caron, founder and executive director of Justice in Motion, an advocacy group actively searching for the parents in Central America.

Caron said Biden has promised to create a government task force aimed at helping reunite the parents and children in his first months in office.

"These families are forever going to be harmed by this policy," Caron said. "We want them to come back to the U.S. and then we want all the families affected by this policy to have legal status in the U.S."

After years of tough talk by Trump about enforcement raids and large-scale deportations, Biden plans to initially scale back forced removals, according to his campaign policy blueprint.

He will take office with an estimated 11 million undocumented immigrants still living in the shadows in the U.S., according to the Pew Research Center.

"Let's legalize their status. Let's make sure that they're on a path to own the American dream as citizens," Noorani said.

But before any path to citizenship, Democrats say a first priority will be shoring up protections for more than 640,000 recipients of Deferred Action for Childhood Arrivals, or DACA. Trump attempted to kill the program, but in 2019 the Supreme Court saved it -- for now.

"I've established my life here in the U.S. I've been here the majority of my life," said Houston emergency medical technician Jesus Contreras, one of an estimated 27,000 DACA recipients on the front lines of the pandemic. "For me to potentially be sent back to Mexico -- quote, unquote my home -- would be devastating, not only to me, but to my community, my employer, my family, my friends."

In the meantime, immigration hardliners are warning a rollback of Trump policies will have dire consequences.

"If you reward the behavior of those coming across illegally, it's going to keep happening," said Morgan.

Biden's critics say moves like rescinding Trump's travel bans on predominantly Muslim countries will pose a security risk, and that expanding visas for foreign workers will only make it harder for out-of-work Americans to find jobs. The new administration vows to take both steps.

"President Trump wants us to be talking about the wall. We as a nation need to be talking about our immigration system," said Noorani. "Without immigrants we would not have the scientists who are developing the vaccines nor would we have those who are caring for our elderly in nursing homes."

For Alvarez, on the front lines of the debate, the presidential transition in Washington is a chance for both sides to refocus on what's most important.

"People have to wait six to 12 hours at a food bank in line to get a box of food. You go to get a COVID test, you have to wait three hours for a COVID test," she said. "I think the wall should be the last thing on people's minds right now."