Authorities will now rely more heavily on immigration law as defined under Title 8 of the U.S. Code. The law outlines the processing of migrants at the border. It allows for expedited removals and penalties such as a minimum five-year bar for reentry.
It will be a significant departure from the use of Title 42, a section of public health law that allowed for fast-track expulsions during the pandemic and carries no such consequences.
"Starting at midnight, people who arrive at our southern border will be subject to our immigration enforcement authorities under Title Eight of the United States Code," Homeland Security Secretary Alejandro Mayorkas said at a White House briefing Thursday afternoon. "Here is what that means. If anyone arrives at our southern border after midnight tonight, they will be presumed ineligible for asylum and subject to steeper consequences for unlawful entry, including a minimum five-year ban on reentry and potential criminal prosecution," he warned.
"The transition to Title Eight processing will be swift and immediate," he said.
The stories and challenges of the migrants who have reached Tijuana, Mexico, are all unique. They come from different countries and continents.
Some of them have been in Tijuana for days, months, even years. Some of them shared their stories with ABC7 this week.
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A roughly 15 minute drive from the city, in a more rural part of Tijuana, is where the Embajadores de Jesus -- or Ambassadors of Jesus -- shelter is located.
About 1,600 refugees and asylum seekers from different parts of the world find shelter there as they wait and hope to seek asylum in the United States.
"People have to know we're living a very complicated situation," Denys Omilien told ABC7, speaking in Spanish. He and his wife Laura, both in their 30s, first immigrated to Chile from Haiti because of sociopolitical threats to their safety.
They traveled through one of the most dangerous paths in the world -- a rain forest region called the Darien Gap, between Colombia and Panama. They had to get rid of their clothes and belongings to make it, traveling through many countries by foot and bus.
In Tijuana, they've found ways to secure clothes, food, and shelter for themselves and their toddler.
For a month, they've tried to schedule an appointment to seek asylum in the U.S. through the method immigration officials have required: a new app called CBP One. The app has proven an insurmountable challenge for most. Among those who can access a phone and internet, there are widespread reports of glitches and limited access, and roughly 800 daily appointments across the entire border.
"There are only three supported languages -- Spanish, English and Haitian Creole, which leaves out tens of thousands of other asylum seekers that speak many other different languages, who have no way to access the asylum process," said Nicole Ramos, director of Al Otro Lado's border rights project. Al Otro Lado is a bi-national advocacy and legal aid organization serving migrants, refugees and deportees in the U.S. and Mexico.
A few hours before ABC7 spoke with Denys and Laura, they were able to schedule an appointment.
Asylum-seeking woman who fled from violence in Michoacán, Mexico, shares her harrowing story
Denys thanked God and smiled, conveying a sense of hope that after a yearslong and perilous journey, that led them to where they were.
Also at the Ambassadors of Jesus shelter, ABC7 spoke with a woman who fled from the Mexican state of Michoacán, a leader in avocado exports, which is a lucrative business for organized crime.
The region has one of the highest rates of homicide in Mexico.
People are plagued by conflicts between armed criminal groups, guerillas and police -- becoming victims of threats, extortion, or worse.
In an interview with ABC7, the woman from Michoacán said her son left to find work for food and water. She was also traveling with two girls, ages 9 and 6.
"They killed my husband," the woman said in Spanish, adding that a guerilla group forcibly recruited her son, who chose to escape by turning himself in to police and serving five years in prison.
They all fled following threats that they would take one of her girls if she didn't turn her son in.
For 25 days, they've lived in Tijuana. Every day, she tries to schedule an appointment through the CBP One. There's never room for a group of four, she said.
Human rights organizations along southern border mobilize to help asylum seekers as Title 42 ends
"My son is in danger," she said. "We can't go back."
In an area adjacent to the border wall, near San Ysidro, a group of asylum seekers camped out while waiting to be processed by U.S. Customs and Border Protection.
A woman named Cynthia, who is from Peru and was travelling alone, said she was worried. As single women, she and others are vulnerable.
Families traveling with small children are understandably prioritized, Cynthia told ABC7, but she herself feared the threat of violence or sexual assault.
Food and water are also scarce, she said. Several people will pitch in to buy one meal. It's one of the many harsh realities that refugees and asylum seekers experience.
"They are facing sort of perilous circumstances in Mexico," Dr. Tom Wong, director of the U.S. Immigration Policy Center at UC San Diego, said in an interview. "They face threats to their physical integrity. They are beaten, they are robbed, they are extorted.
"And so, human rights organizations like Human Rights First have documented hundreds and hundreds of cases of abuse of asylum seekers while in Mexico as they try to enter the United States."
The center is currently working to obtain Freedom of Information Act data on the national origin of those who successfully schedule an interview and subsequently have that interview using the CBP One app.
"We want to think about user experience, and how that user experience may or not be equitable," said Wong.
Human rights organizations across the border are mobilizing to document and respond to the challenges asylum seekers may experience. One concern is over what will be an expedited processing of asylum cases which could lead to expedited removals.
"People will be forced into having a 'credible fear interview,' with an asylum officer, directly at the port of entry, which is one of the plans that the administration has indicated it will be implementing," said Nicole Ramos of Al Otro Lado. "Which means people will not have the opportunity to have meaningful access to attorneys to consult about their claim -- whereas people who must appear for their asylum case at a later date, before immigration court will have time to consult with attorneys and bring an attorney to that hearing."
ABC News contributed to this report.