BASTROP, Texas —By the time she reached school on a recent Monday morning, Norma Mercado had already driven four homeless children to class, one from 30 miles away, having spent the weekend taking a group of homeless students on a college tour and two homeless siblings to buy clothes.

Inside her office, a student was waiting, boiling with rage. Louisa Perez’s ex-best friend was insulting her on Facebook, and Ms. Perez, 17, who until recently had been living in a car, considered the betrayal the latest in a life of violated trust. “That’s why I feel like I can’t be close to nobody — because this always happens!” she sobbed. Friends were urging her to fight.

“Oh, my goodness,” Ms. Mercado said. “Sounds like you’re super mad.”

With a voice as placid as the room was disturbed, Ms. Mercado spent a half-hour urging restraint, then sent Ms. Perez to class while making a mental note to keep watch, uncertain if the instinct to fight had flamed out or would reignite.

For hundreds of poor families in this rural district outside Austin, Ms. Mercado is a one-woman rescue squad — a source of food, clothes, transportation and counsel — with a gift for keeping homeless students in school. She is also a reminder of the scale and complexity of student homelessness and an exemplar of a little-known federal program that is suddenly awash in funds to help disadvantaged students succeed.

Under a 1987 law now known as the McKinney-Vento Act, every school district must appoint a “liaison” like Ms. Mercado to protect homeless students’ rights. But until now only about one district in four received money for the work, meaning many made perfunctory efforts. With school closures from the pandemic harming poor students, Congress last year approved $800 million in new grants, more than tripling the funding for three years and auguring an era of innovation in services for homeless children.

“It’s like winning the lottery,” Ms. Mercado said.

Thousands of districts are receiving money for the first time, while others, like Bastrop, are expanding their work. Ms. Mercado is hiring a second caseworker and a contractor to provide mental health care.

The explosion of services nationwide — dental care, tutoring, school supplies, arts programs, cabs — shows how often school systems act as de facto social services agencies. But as with other Covid-era relief, temporary funding makes planning difficult and portends problems when the money disappears.

Thirty-five years after its creation, the growth of the McKinney-Vento program evokes the degree to which homelessness has become a routine feature of American life. Across the country, schools that once denied they had homeless students consult federal rules to serve them, and “homeless liaison” is a profession so established that it has its own training and advocacy group. Nationally, the McKinney-Vento population stood at nearly 1.4 million before the pandemic, about 2.7 percent of all students.

Few liaisons are as saturated with the mission as Ms. Mercado, whose phone buzzes with requests into the night and whose caseload shows how profoundly the lack of stable housing threatens education. Like Ms. Perez, her students sleep in shelters, tents and unheated trailers, and wear out welcomes among relatives and friends.

“How can you go home at night and not worry about these children?” Ms. Mercado said.

Homeless as a child herself, pregnant at 15, Ms. Mercado is now pursuing a Ph.D. — she is a homeless liaison writing a dissertation about homeless liaisons. The journey has steeped her in the faith that every student can succeed.

“I know how it feels, being homeless, being poor, being pregnant as a teen,” she said. “These students just need someone to tell them they are smart enough, they are beautiful enough. They deserve the very best.”

Growing Needs, Growing Services

To follow Ms. Mercado around this rural district, 30 miles from Austin, is to behold the startling variety of ways that students become homeless.

Yaritza Saucedo came home from fifth grade to find her home had vanished. Her family’s trailer had been repossessed — with her dog inside. Another student learned it was time to leave a neighbor’s house when the neighbor locked the refrigerator and tossed his clothes on the lawn. Part of Ms. Mercado’s work involves counseling parents who evict their children upon discovering they are gay.

With 759 children on her caseload and counting, Ms. Mercado serves about 6 percent of the district’s students. She calls them her “kiddos.” They call her “Miss Norma” or simply “Miss.” (One word Ms. Mercado normally avoids is “homeless,” saying it stings; she prefers “students in transition.”)

Before Congress acted in 1987, students who lacked stable housing routinely struggled to stay in school. Many did not have the documents needed to enroll, like birth certificates and vaccine records, and frequent moves often left them without transportation. Some changed schools by the month.

Initially the law merely required school systems to review their policies toward homeless students, but later versions gave students concrete rights. Officials must immediately enroll them (and collect the paperwork later); make efforts to let them stay at their schools (even if they leave the attendance zone); and provide transportation (sometimes from other school districts).

As federal grants grew, the McKinney-Vento framework added services, like tutoring or school supplies. And in fostering a network of advocates like Ms. Mercado, the law has had the less obvious effect of raising awareness of homelessness.

“The fact that there’s this cadre of liaisons who are committed to the program has pushed schools to pay more attention to homeless kids,” said Maria Foscarinis, a longtime housing advocate who lobbied for the 1987 law.

While only about 57 percent of homeless children were enrolled in school when the law passed, the share soon rose to 87 percent.

Still, homeless students do worse in school than other poor students, and their numbers have roughly doubled over the past 15 years. Government figures from 2017 showed that 13 percent of students were homeless in New York and Santa Ana, Calif., the large cities with the highest rates. Nationwide, nearly 80 percent of homeless students are temporarily living with friends or relatives, with the rest in shelters, motels, tents or cars.

Ms. Mercado’s work is emblematic of the program’s expansion of services and has attracted broad support in Bastrop County, a region with conservative leanings. She has supplemented modest McKinney-Vento aid — past grants of $60,000 a year provided about $80 for each student she serves — with other federal funds and private donations.

While some liaisons struggle to get high-level support, Ms. Mercado lauds the district’s leaders for empowering the work, and they laud her. “When you have someone who is so devoted to doing what’s best for students, it makes it an easier decision” to provide funding, said Barry Edwards, the Bastrop superintendent.

Racks of donated shoes and clothes fill a classroom renovated by the Rotary Club, and private donors cover activities that federal rules preclude, including an annual restaurant meal where students practice dining etiquette. Still, Ms. Mercado often spends her own money on food, blankets, caps and gowns, gas cards and beds, and it took an older colleague to urge her to let go at the end of the day.

“When I first started this job, I would get very overwhelmed because you see so much trauma, so much pain,” she said. “Now I’ll say, ‘God, you’ve got the wheel — in the morning I’ll be here again.’”

‘An Angel on Earth’

To grasp the scope of Ms. Mercado’s efforts, consider her work with Maria Bustos Lopez, 68, and the three young grandchildren she and her husband are raising. After he had a stroke last year, the couple missed payments on their rented lot, and their landlord towed their trailer to the side of a busy highway. When Ms. Mercado found them with no electricity or water, Ms. Bustos sobbed, fearing she would take away the children.

Instead, Ms. Mercado got the children in school for the first time in months. She sent a bus to pick them up. She delivered food and electric blankets and gave them their pick of the clothing closet. When the family found a new lot far from a bus stop, a church donated bikes so the children would not have to walk.

On a recent visit, Ms. Mercado discovered the refrigerator was not working. A week later, she delivered a new one, courtesy of the Salvation Army.

“Norma has been an angel on earth,” Ms. Bustos said.

Ms. Mercado goes out of her way to try to make school employees more conscious of housing problems. One student was forced to attend summer school after ignoring an assignment to draw her own house. The teacher did not realize, until Ms. Mercado explained, that the student lived in such squalor, with pirated electricity and water drawn from a neighbor’s hose, that she was too ashamed to depict it.

By contrast, Ms. Mercado celebrates the generosity of another teacher, Mirella Hernández Spalding, who learned Ms. Mercado needed a home for a displaced teenager. The student, Jennifer Hurtado, was born in the United States but raised in Mexico after her mother was deported. An aunt invited the teenager to attend high school in Texas, then put her out. After one brief meeting, Ms. Spalding let her move in.

“My heart melted for Jennifer from the very beginning,” Ms. Spalding said.

Ms. Hurtado, who arrived speaking no English, rapidly became fluent, finished high school in two years and is seeking to become a border guard, in hopes of improving cross-border relations. She still lives with Ms. Spalding and her husband, who have also taken in her brother, and she credits Ms. Mercado for finding her an “awesome” adoptive family.

“I’d be back in Mexico without Miss Norma — I didn’t have anywhere to go,” she said.

While many of Ms. Mercado’s students have known only poverty, Gwendolyn Ibarra, 17, fell into homelessness after her mother left her stepfather and moved with her children to a shelter.

Preternaturally poised, Ms. Ibarra, a straight-A student, has taken seven Advanced Placement courses, led the National Honor Society at her school, spent four years playing saxophone in the band, endured 7 a.m. practices for drill team and served as a youth adviser to the City Council. But she wrote her college applications last fall from six different addresses.

“You never expect it to happen to you,” she said of homelessness.

Ms. Mercado supplied Ms. Ibarra with shampoo and clothes and arranged transportation so she could avoid switching schools, even when her unsettled existence took her to Austin. She helped her get a driver’s license and apply for financial aid through a process that waives paperwork for homeless students. And she did it, Ms. Ibarra said, “in a way that was completely judgment free.”

An aspiring neuroscientist, Ms. Ibarra was still on the district’s list of homeless students last month when she accepted an admissions offer from Harvard.

Without Ms. Mercado’s support, she said, “I don’t think I would have even applied.”

If Ms. Mercado sees promise in homeless children, that is partly because she sees herself in them. Joining her mother, an undocumented farmworker, on childhood journeys from Mexico to California, she survived homelessness on both sides of the border and sexual abuse from a relative. At 15, she made an unauthorized trip across the border to join her mother in California, where she quickly became pregnant.

When her mother forced her to leave, she was homeless again, as well as undocumented and afraid. Her baby was stillborn, and compounding her distress was the disdain she felt from workers in the Medicaid office and counselors at school.

“I remember sitting there and just thinking, ‘One day I’m going to be in your seat and I’m not going to treat people this way,’” she said.

Gaining legal status through an amnesty passed in the 1980s, Ms. Mercado married her teenage boyfriend — they have five children — and said her involvement with an evangelical church, where her husband serves as co-pastor, helped heal childhood scars. The journey has taught her to look past her students’ traumas, she said, and see “the strong, resilient people they can become.”

When the Money Runs Out

New funding expands the chance to build that resilience. Congress acted last year after a study found that early in the pandemic, 28 percent of McKinney-Vento students had disappeared from the rolls. Senator Lisa Murkowski, Republican of Alaska, led the bipartisan effort to increase funding, with support from Senator Joe Manchin III, the West Virginia Democrat who later blocked President Biden’s larger anti-poverty plans.

While providing more money, Congress also let school districts use it for broader purposes.

Since homelessness as a child predicts homelessness as an adult, supporters see a rare chance to break the cycle. “If we do this right, we’ll have more homeless students finishing school and ultimately less homelessness,” said Barbara Duffield, who leads SchoolHouse Connection, a nonprofit group.

Cincinnati hired a specialist to help families find housing aid. Mobile, Ala., is financing short-term motel stays. Minneapolis is sending cabs to keep students in schools while they await new bus routes.

Bastrop is among the many places focusing on mental health. Citing increased anxiety and depression during the pandemic, Ms. Mercado has hired the Y.W.C.A. to offer group therapy to students and parents. The move is possible because the district’s funding has grown to about $150,000 a year, two and a half times the previous sum. Ms. Mercado said a recent experiment, with a social work intern providing the therapy, proved the sessions’ value.

“A mental health provider can be the difference between life and death,” Ms. Mercado said.

But what happens in three years when the extra money runs out?

Some advocates hope the program’s success will compel continued funding, from Congress or philanthropy. Ms. Mercado simply pledges to soldier on. “Whether there’s a lot of money, or no money, students need us so we’re going to be there,” she said. She sits beside a bulletin board papered with notes from families she has aided and the funeral program of a student who escaped her grasp.

What It Takes to Help

While Ms. Mercado tends to hundreds of students, special effort goes into one — Ms. Perez, the teenager distraught at the Facebook taunts. If Ms. Mercado’s devotion reflects her faith that everyone can succeed, it also shows the extraordinary support progress may demand.

Placed in foster care at an early age and later sexually assaulted, Ms. Perez arrived in Ms. Mercado’s office nearly three years ago, after her release from a mental hospital. She was 15 years old, volatile and pregnant — the kind of student some educators dread.

Ms. Mercado took to her instantly. “Because of my past, I could just feel how much she was hurting,” she said.

Ms. Mercado provided clothes, took Ms. Perez to the doctor and held back her hair when morning sickness caused her to vomit. Ms. Perez lost the pregnancy — after a boyfriend kicked her in the stomach, she said — but the bond with Ms. Mercado persisted.

Ms. Mercado got her into counseling and urged her to end a violent relationship. When she could not endure regular classrooms, Ms. Mercado placed her in an alternative school. When she ran away with a new boyfriend, Ms. Mercado found her and supplied a laptop. When she lived in a tent and a car, it was Ms. Mercado she called.

“Miss Norma has been there for me more than my own mom,” Ms. Perez said.

Now living with her boyfriend and his grandfather, Ms. Perez is regularly in school for the first time since seventh grade and is on track to graduate this spring — on schedule, she notes. She arrives early most days to talk to Ms. Mercado, whom she calls “my sweet escape.”

Still, crises persist. Though Ms. Mercado persuaded Ms. Perez not to fight over the Facebook taunts, the danger of the moment became clear the next day: A friend who took her place in the feud came to school with stitches in her head. When a conflict with the principal erupted — Ms. Perez refused to be in the same room with him, saying his projection of male authority reminded her of “the men who raped me” — Ms. Mercado worked out an elaborate protocol for a video call.

On a recent morning, Ms. Perez sat in Ms. Mercado’s office and spoke with unusual candor about the trauma she survived: the molestation, the homelessness, the miscarriage she still mourns. Ms. Mercado, who had been half-listening, suddenly jumped in.

“Wait, wait — you just said all this without crying!” she said. “That means you’re healing!”

Ms. Perez glowed. “Thank you, Miss Norma!” she said.

“That’s what drives me,” Ms. Mercado later explained, “to see these students get hope.”