Vargas, a Pulitzer Prize-winning journalist and the director of Documented, was detained by border patrol officials when he tried to fly out of an airport in McAllen, his spokesman, Ryan Eller, said.
"It became apparent during our time here in McAllen that [Vargas] may not be able to leave," Eller said. "For thousands, this is a daily struggle."
Brought to the U.S. from the Philippines at the age of 12 by his grandfather, Vargas only learned he was undocumented when he tried to apply for a drivers license when he turned 16 and was told his permanent residency card was a fake. He revealed his undocumented status in 2011 in the New York Times.
On Friday, Vargas published an essay from McAllen, revealing his realization that his decision to travel there had exposed him to arrest.
"I flew into the valley Thursday morning to visit a shelter for unaccompanied Central American refugees and participate in a vigil in their honor," Vargas wrote.
"When my friend Mony Ruiz-Velasco, an immigration lawyer who used to work in the area, saw on my Facebook page that I was in McAllen, she texted me: "I am so glad you are visiting the kids near the border. But how will you get through the checkpoint on your way back?" A curious question, I thought, and one I dismissed. I've visited the border before, in California. What checkpoint? What was she talking about?"
"Then Tania Chavez, an undocumented youth leader from the Minority Affairs Council, one of the organizers of the vigil, asked me the same question: "How will you get out of here?" Tania grew up in this border town. As the day wore on, as the reality of my predicament sunk in, Tania spelled it out for me: You might not get through airport security, where Customs and Border Protection (CPB) also checks for IDs, and you will definitely not get through the immigration checkpoints set up within 45 miles of this border town. At these checkpoints, you will be asked for documentation."
Vargas does not qualify for the Deferred Action for Childhood Arrivals program, begun by President Obama and aimed at "dreamers" who arrived before the age of 16 and are under the age of 31. He does not have a U.S. government-issued ID, and traveled only with a Philippines passport and a copy of the U.S. Constitution.
"Identification aside, since outing myself in the New York Times Magazine in June 2011, and writing a cover story for Time a year later, I've been the most privileged undocumented immigrant in the country," he said. "The visibility, frankly, has protected me."
"About to go thru security at McAllen Airport," Vargas tweeted Tuesday morning. "I don't know what's going to happen."
Several minutes later, he was photographed in handcuffs being taken to detention by customs officers.