Maria Castaneda's earliest memory is a ghostly haze of sand and rocks and movement.

She was 3 years old when she left central Mexico in her mother's arms, unknowingly embarked on a dangerous journey north. They were part of a group that crossed the border on foot in Arizona, then headed east by car to North Carolina, where her father had settled after a similar trek.

Today, at 22, Castaneda has achieved a true American dream: She's a senior at Swarthmore College, succeeding at one of the nation's elite schools and on track to a fulfilling career in education or law.

Now, she's wondering if it will all be stripped away.

The Trump administration's decision Tuesday to end an Obama-era program that protects 790,000 undocumented immigrants from deportation has been condemned and praised. But people like Castaneda are the ones facing the potentially life-changing consequences.

The federal initiative, called Deferred Action for Childhood Arrivals, or DACA, allows immigrants who were illegally brought here as children to register with the government — and contribute by holding jobs and paying taxes without fear of being expelled from the country where so many grew up.

In announcing DACA's revocation, Attorney General Jeff Sessions said the nation must set and enforce a limit on how many immigrants can be admitted each year. Not all can come.

But DACA advocates say people such as Castaneda embody the heart and grit of earlier generations of immigrants, people who trusted in America's promise and forged new and better lives in an unfamiliar land.

The announcement sent Castaneda through a range of emotions — anger, sadness, uncertainty.

"But I woke up this morning, and I still have to go to class," she said last week. "No matter what's happened, we continue to survive, we continue to find ways to succeed in this country, and we're going to keep advocating."

How does someone get from the valleys of central Mexico to the lush gardens of Swarthmore? The hard way.  It's a journey measured in more than miles.

Both of her parents grew up in the state of Michoacán, in the same 1,000-person pueblo where food could be scarce and shoes a luxury.

Later, as a couple, they scratched out a living as vegetable farmers. When corn prices dropped, they did what others had done and left.

"You have to imagine how bad it is, that you can't feed your kids," Castaneda said. "No money. No jobs. … That desperation drives you because it's your only choice."

Castaneda entered public school in North Carolina — late, because the community had no Spanish-speakers, and her parents initially didn't know how to enroll their only child. She graduated with top grades.

Castaneda knew that she wanted more education, and that she would be leaving the area to get it.

North Carolina public universities charged undocumented students the higher, out-of-state tuition rate. And South Carolina specifically banned undocumented students from enrolling or receiving public grants and aid.

Swarthmore, a private school, encourages applications from all students, regardless of citizenship status. The school doesn't consider the financial needs of undocumented and DACA students when making admissions decisions but is committed to covering all costs for those who are selected. That includes Castaneda, whose education is funded by the college.

When she arrived in 2014, she was one of two DACA students. Now there are 23, she said.

Her family is what people in immigration circles call mixed — that is, having a variety of legal statuses. Her parents, who work at a North Carolina turkey farm, remain undocumented. Her two younger brothers were born here and are U.S. citizens.

Nearly 70 percent of DACA recipients were 10 or younger when they arrived, according to the Brookings Institution. Seventy-seven percent came from Mexico, 10 percent from El Salvador, Guatemala, and Honduras.

Applying for citizenship is not an option for many DACA young people, 5,889 of whom live in Pennsylvania. Changes to U.S. law have made it almost impossible for immigrants to obtain legal status if they have lived in the country illegally.

For them and others, the clock is ticking.

Trump granted a six-month delay to give Congress time to craft a solution on DACA — and later said he would "revisit" the issue if legislators failed to act.

Meanwhile, no new DACA applications are being accepted.

Castaneda wants to make her life in America. But if forced to leave, she said, she knows she could survive in Mexico, that after battling for success in this country she would find a way to flourish in that one.

Castaneda has another memory of her arrival in the U.S.  An Independence Day fair. That's how she knows her family reunited in an early July. She can still picture the glowing lights of the Ferris wheel and the glare of the fireworks —the red, white, and blue celebration.

"It's almost symbolic, metaphorical — I got to see all the American symbols," she said. "I always think about that, how it was almost ironic."