TEXARKANA — New buildings are shooting up around the sun-baked grounds of the Texas A&M University System’s northernmost outpost here.

There’s a $32 million glass-fronted complex near completion that will house the nursing program and administrative offices and a new $11 million recreation center that will also have a lab to study kinesiology, or human movement.

Texas A&M-Texarkana may be the smallest of the system’s 11 campuses, but it’s been growing steadily. Enrollment at the beginning of the academic year that just ended was up 13 percent from 2014, to 2,038.

While the number of students has been rising, however, so has the proportion who begin as full-time freshmen but fail to come back for a second year. Fifty-five percent who started in 2015 were gone by the following year, the most recent period for which the figures are available, according to U.S. Department of Education data analyzed by The Hechinger Report. That’s up from 44 percent two years before.

“There are some people who have situations, who get pregnant or financial things change,” said Caleb Sparks, a double major in biology and electrical engineering hanging out between classes in the air-conditioned student center.

“I know of people who have left because they didn’t want to be in college,” added Amber Spence, who earned her undergraduate degree here and is now a graduate student. “Their parents made them go.” And even on a small campus where students greet each other by name, she said, “There are still individuals who feel lonely and isolated.”

These and other challenges mean that, at a time when growing proportions of high school students have been successfully encouraged to go on to college, more than one in five full-time freshmen nationwide fail to return for a second year, according to the data.

That, in turn, contributes to the fact that more than a third of students who start college still haven’t earned degrees after six years, the National Student Clearinghouse Research Center reports, often piling up loan debt with no payoff. Those who disappear for good cost colleges and universities — including taxpayer-supported public ones like Texas A&M-Texarkana — billions of dollars in lost tuition revenue.

Students who are the first in their families to go to college are the most affected. Three years after enrolling, one-third had quit, compared to about a quarter of students whose parents have a university degree, the Education Department reports.

Yet even as attention has begun to be focused on this problem and its massive cost, the numbers are barely improving, The Hechinger Report found. At some types of institutions, they’re flat or getting worse, according to the data.

“It’s not just about getting them in the door. It’s about making sure they come back from one year to the next,” said Eboni Zamani-Gallaher, a professor of higher education policy, organization and leadership at the University of Illinois at Urbana-Champaign College of Education. “That’s the conundrum we still haven’t gotten figured out yet.”

In a trend that has been widely lauded, the proportion of high school graduates who go straight to college has increased from 63 percent in 2000 to 70 percent now, the U.S. Department of Education says.

But the proportion of full-time, first-time students who return for a second year, either full or part time — a measure called retention — has improved only slightly at public four-year universities, where it is up by 2.6 percentage points since 2011, the federal data show. At private nonprofit colleges, it’s up by just 1.3 percentage points. And at private for-profit colleges and universities, more than 44 percent of students leave before finishing, a figure that is eight-tenths of a percentage point worse than it was in 2011.

In all, more than a million students a year quit college, according to the consulting firm ReUp Education, which helps universities with the time-consuming and expensive process of trying to find and re-enroll them. Some may transfer and finish somewhere else; the federal figures don’t track that. But many are assumed to have dropped out.

That’s partly because schools have historically focused more on recruiting students than on keeping them, said Alan Seidman, founder and director of the Center for the Study of College Student Retention, who once worked as an admissions director.

“It was my job to get students enrolled, and if you didn’t enroll them, your job could be on the line,” he said. There was no such incentive for retention, he said. “So philosophy follows finance, rather than the other way around.”

New realities are conspiring to make higher education institutions try to finally fix this.

One is that legislatures and governors in many states are tying university budgets to such things as retention. At least 32 states now make funding contingent on success rates, according to the National Conference of State Legislatures, including the number of degrees awarded and student progress toward degrees.

Another: Employers are impatient for qualified graduates to hire. “People are talking about shortages in the workforce,” said Zoë Corwin, a researcher at the Pullias Center for Higher Education at the University of Southern California. “I’m optimistic that there’s been a national shift in awareness in how we think of this, so that’s promising.”

But the biggest reason for the new focus on preventing students from leaving is that colleges are starting to run out of them.

While a larger percentage of high school graduates are going on to higher educations, their actual numbers have declined dramatically, and the number of older-than-traditional-age adults on campus is also down as more are drawn back into the thriving labor market.

These trends together mean that there are nearly 2.9 million fewer college students than there were at the most recent peak, in 2011, the National Student Clearinghouse reports. That makes institutions “a little more sensitive to retention,” Zamani-Gallaher said.

After all, the plummeting number of prospects makes it much harder to replace dropouts than it was when there was a seemingly bottomless supply of freshmen.

“There’s a growing notion that we need to change the business model, and the reason it needs to change is there’s not a never-ending flow of high school graduates,” said Bruce Vandal, senior vice president at Complete College America.

Students who leave are also costing colleges significant amounts of money in forgone tuition — $16.5 billion a year collectively, according to a review of 1,669 institutions by the Educational Policy Institute, or $13.3 million for the average public and nearly $10 million for the typical private college or university. Those are big hits for campuses already struggling to close budget shortfalls.

Yet colleges remain focused on recruitment, “which they already know how to do,” said Andrew Nichols, senior director of higher education research at The Education Trust. “It’s harder work to retain students.”

They may no longer be able to avoid it.

While state higher education funding in Texas doesn’t consider institutions’ retention rates, the Texas A&M System makes them glaringly public in an online dashboard.

“The world of higher education has really changed about this,” said Emily Fourmy Cutrer, president of A&M-Texarkana, where student persistence is the lowest of the system’s 10 campuses. “We are under more pressure for retention and graduation.”

Reminders have popped up all around the campus about a website called Degree Works, which tells students which requirements they’ve satisfied and what’s still left to do. “Not sure you’re on the right track for graduation?” it calls out to passersby from among notices on bulletin boards advertising class rings and intramural ultimate Frisbee.

There are also tutoring centers and a program called Personal Achievement Through Help, or PATH, to keep black male students on track. While college enrollment for black men is up, according to the U.S. Department of Education, black students in general graduate at lower rates than others, the College Board reports; at a third of colleges and universities studied by The Education Trust, graduation rates for black students have been flat or falling, and men of all races graduate at lower rates than women except at for-profit universities.

“They have all these safety nets — tutoring, advising,” said Camryn Davis, an A&M-Texarkana sophomore majoring in biotechnology. “We actually do get flags when the adviser forces you to come and see them.” Those kinds of reminders happen “pretty much all semester,” said Hailee Witten, a senior education major. “There’s posters, there’s emails. They hag you.” Witten stopped to reflect on whether she just made up that word, but then described it as a combination of “hassle” and “nag.”

This aggressive response has helped lower the dropout rate at the Texarkana campus back to 44 percent, according to still-unreleased figures, the university says. Between the fall and spring, it said, only 11 percent of students left, a record low.

“We have interventional advising, and that’s not a bad thing,” Cutrer said. She said supporting students has become a top priority. “Woe to the faculty member who says, ‘My class is a weed-out class.’ That is not a thing any more.”

But making further headway is stymied by the nature of the problem. Colleges don’t always know someone is in danger of leaving until he or she stops showing up. It’s also difficult, under a federal ban on tracking individual students, to know if they enrolled or finished somewhere else.

Nor are academic problems necessarily the major reason students quit. More than 40 percent who leave have grade-point averages of at least 3.0, or a solid B, according to the education consulting company Civitas Learning. A separate report from the Georgetown University Center on Education and the Workforce estimates that 500,000 top-scoring high school graduates spanning all races and income levels never earn degrees, most of them because they start but then give up on college.

“It would be great to do an exit interview,” Zamani-Gallaher said. “But we don’t have the benefit of knowing in advance that a student is leaving. We have this lag time in realizing they’re not here.”

Or, as one undergraduate who quit put it, “Leaving was weird. Nobody noticed.”

That comment came in response to a rare endeavor by a higher-education institution: a survey emailed to 10,555 students in 2014 by the University of Washington to learn why some left before graduating.

Many of those who answered — fewer than one in five who received the survey, in spite of a chance at a $200 gift card — said they ran into financial problems or worried about falling too deeply into debt. Forty-one percent said they felt isolated or alone, and 39 percent that they didn’t think they were getting their money’s worth. Racial and ethnic minority students were particularly likely to report that their scholarship money ran out or was not renewed, that their families needed them or that the university wouldn’t let them continue because they fell behind in their payments.

Many students balance college and jobs. Cutrer, who teaches a freshman seminar, said six students in her class of 20 told her they worked 40 hours a week, eight worked 30 or more hours and the rest worked at least part time.

“If it’s between earning money and going to class, I’m going to earn money because I have to support people,” Seidman said. Students “don’t understand the cost-benefit of going to college” — the typically higher wages earned by degree-holders — “and we do a bad job of explaining that.”

Another problem is poor preparation that requires remedial education, usually in math or English. At least half a million students a year are placed into such courses, The Hechinger Report has found, and many of them give up in frustration, according to the advocacy organization Complete College America. This, too, hits nonwhite and low-income students hardest; 44 percent of black, 37 percent of low-income and 35 percent of Hispanic students are diverted into remedial classes at four-year universities and colleges and significantly larger percentages at two-year ones.

Black and Hispanic students also disproportionately enroll at community colleges and regional public universities that can’t afford to provide the level of support that better-funded private colleges and public flagships can, a new report by the Center for American Progress shows.

“Access without success is not really solving the problems we need to solve, especially for the most disadvantaged,” said Vandal.

Additional reporting by Dana Amihere. This story was produced by The Hechinger Report, a nonprofit, independent news organization focused on inequality and innovation in education.

Disclosure: The Texas A&M University System has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune’s journalism. Find a complete list of them here.