— A small state school launched here in the 1960s to develop employees for the space program has morphed into one of the nation’s largest universities, using accessible admission policies and online instruction to fuel extraordinary growth in an era when many public colleges face fiscal uncertainty.

The University of Central Florida will have about 54,000 undergraduate students this fall, up 90 percent since the turn of the century. The only public university with more is Arizona State, counting at least 67,000 on five campuses.

UCF and ASU are in the vanguard of an insurgency that aims to demolish the popular belief that exclusivity is a virtue in higher education. They stand for access on a grand scale, arguing that breakneck growth serves a nation in desperate need of a better-educated workforce. They also are pursuing a new financial model that enables public universities to thrive even when state support dwindles.

Their solution, possibly a blueprint for others around the country, combines a bustling traditional campus with an ever-widening menu of online and semi-online courses. And they’re doing it at a relatively low price.

“Our concern is that qualified students who want to get a college education be allowed to do so,” UCF President John C. Hitt said. “We’ll do our part in that, to the best of our ability. We do recognize that there is a limit. We just don’t know where it is.”

Many UCF students are first in their families to go to college, and thousands arrive every year from community colleges.

“We don’t have enough of these examples,” said Andrew P. Kelly, a higher education analyst at the American Enterprise Institute. “It’s a rare sight to see institutions self-consciously trying to build capacity to serve more students. The incentives tend to point in the opposite direction, toward exclusivity. These guys are breaking the mold.”

The beneficiaries are students such as Claudie Milien, 18, from West Palm Beach, Fla. His mom is a caregiver, his dad a golf caddy. Neither earned a bachelor’s degree. Milien aims for one in computer science. The price is right: In-state tuition and fees at UCF are $6,368 this year. So is the size.

“I like that it’s huge,” Milien said at a recent rally for new students. “There’s so many things you can do here. If you have an interest, most likely you’ll find it.”

Claudie Milien, left, 18, and Bill Noel, 18, listen to speakers during the convocation for incoming freshmen in the CFE Arena at the University of Central Florida in Orlando on Sunday, Aug. 23, 2015. (Phelan M. Ebenhack/for The Washington Post)

Knightro, the UCF mascot, slaps hands with Alex Hindman, 18, third from right, and Jade Matthies, 18, second from right, during the convocation for incoming freshmen. (Phelan M. Ebenhack/for The Washington Post)

There are downsides. Central Florida’s student-to-faculty ratio is one of the highest in the country, at 31 to 1 as of 2013. The norm for public universities with at least 20,000 students is 19 to 1.

Some classes on the sprawling campus are so packed — with as many as 1,000 students — that there are only enough seats to handle a fraction of them. The rest watch online or squat in the aisles. Such “lecture-capture” courses and others with online elements aim to bolster teaching capacity and give students flexibility. Some students juggle classes and jobs. Others don’t want to attend lectures.

Elizabeth Connor, 23, who graduated this year with a bachelor’s degree in management, said the size of one class shocked her when she first arrived.

“Mom, I don’t think I can do this,” she recalled saying in a phone call home. “There’s 700 people in my business class!” But she grew to like the format because she could rewatch lectures if she got confused. “I never missed a beat.”

UCF officials say three-quarters of undergraduate classes have fewer than 50 students. But they acknowledge more professors are needed. Plans are underway to expand tenured and tenure-track positions 25 percent over two years.

Many colleges have the opposite problem and are scrambling for students. Small private schools often face real jeopardy if they can’t recruit a large-enough student body. Tiny Sweet Briar College in Virginia, more than a century old, this year barely avoided shutdown.

Elite private universities, on the other hand, turn away tens of thousands of applicants a year. These schools are growing little, if at all. Stanford and Princeton have talked recently about possibly adding a hundred or so students per class. At UCF, that amounts to a rounding error.

Public universities dominate the college market, but tight state budgets and policies geared toward selectivity often cap growth. The median undergraduate growth rate for state flagships from 2000 to 2013, federal data show, was 18 percent. At the University of Virginia it was 17 percent, and at the University of Maryland it was 8 percent.

The University of Florida, up the road from here in Gainesville, grew 1 percent, while the state’s population grew 20 times as much. The surge in young adults seeking entry to college created an opening for the upstart UCF on the east side of Orlando.

To Floridians, UCF is well known, but nationally it flies under the radar. It ranks 168th on the U.S. News and World Report list of national universities. The school drew attention in January 2014, when the football Knights reached the Fiesta Bowl, upsetting Baylor 52-42 and finishing in the national top 10.

One of its most famous alumni is comedian Daniel Tosh (class of 1996), an analyst of Internet videos on Comedy Central; another is economist R. Glenn Hubbard (class of 1979), an architect of President George W. Bush’s tax cuts.

What was originally called Florida Technological University opened in 1968, a year before astronauts journeyed to the moon from a launch pad east of here. Walt Disney World opened to the southwest in 1971, a major catalyst for the region.

But when Hitt took over in 1992, UCF was still a modest commuter school, with 18,000 undergrads. He set about rebuilding the sun-drenched campus. The joke here is that the initials stand for “Under Construction Forever.”

John Hitt, president of the University of Central Florida, talks while sitting in front of a map of the UCF campus on the first day of classes of the fall semester in Orlando, Monday, Aug. 24, 2015. (Phelan M. Ebenhack/for The Washington Post)

Early on, Hitt pushed to join the NCAA’s highest level of football.

“If you’re a state university in the South, and you want to be taken seriously, there are several things you do,” he said. “You do a fair amount of research. You award a fair number of PhDs. And you play Division I football.” The university also built a 45,000-seat stadium. Those are typical brand-building moves.

Less typical was UCF’s plunge in the late 1990s into online instruction. Hitt said he wanted to ease a bottleneck: Too many students had trouble getting their final credits for graduation. So UCF started putting courses online. “That made a big difference in letting us continue to grow,” Hitt said.

Whether they live on campus or commute, students now can take classes that are fully online, fully face to face, or a mix of the two. Faculty say the wired generation is sometimes more engaged online. “They’ll text you or write you more than they might raise their hand in class,” said Amy Gregory, an assistant professor of hospitality management. “There’s safety in being on the other side of the device.”

The increasingly sophisticated online operation helped UCF expand even during years of economic recession, when state funding grew lean. Another key to growth: UCF guarantees admission to local community college graduates. More students enter every fall as transfers than as freshmen.

“I was trying to save as much as I possibly could,” said Wisangeles Walker, 21, a transfer student from Seminole County. Like 20,000 others here in financial need, she receives federal Pell grants.

The daughter of Jamaican and Puerto Rican parents, Walker is a first-generation college student. She promised her mother she would go to college before her mother died of leukemia three years ago. A management major, Walker just finished an internship with Frito-Lay and hopes that will lead to a job offer. She also is president of a club called the Transfer Knights and goes to football and basketball games to soak up what she called “the real college experience I was looking for.”

What will a bachelor’s degree mean for Walker?

“Everything,” she said. “Being able to provide for myself. Making my mom proud. It means everything to me.”

Jessica Roberts, 19, a first-generation student in psychology, manages the pantry of a campus charity called Knights Helping Knights. It distributes free food and clothing to those in need. “You feel good knowing that you’re really helping people,” she said.

Ivey Padgett, 20, a computer science student, is helping to start a computer club called Knight Hacks. Her dad is an electrician, her mom a homemaker. They didn’t go to college. “They’re so proud,” she said. “They brag about me all the time. I tell them, ‘You guys, you don’t have to tell the pharmacist.’ ”

A student stands under an arch of the Rosen College of Hospitality Management building at the University of Central Florida in Orlando. (Phelan M. Ebenhack/For The Washington Post)

Students make their way along a raised walkway built over a natural wetland behind the student union building on the first day of classes for the fall semester. (Phelan M. Ebenhack/For The Washington Post)

UCF officials say wider access does not mean lower standards. The school admits fewer than half of its freshman applicants. Grades and test scores of those admitted have risen over the years, and the incoming class includes 69 National Merit Scholars. The six-year graduation rate (70 percent) is about 10 points higher than the national average. The school also fares well in competition for what Florida calls “performance funding” — effectively a public bonus pool for state universities.

Michael M. Crow, president of Arizona State, says his school and UCF are pointing the way to a new era for American universities that are bigger and more diverse than ever, but also research-intensive. The nation’s needs, he said, can’t be met through small liberal arts colleges.

Bigger can be better, Crow and Hitt say.

“If you vary from the norm of a few professors gathered around a few students,” Crow said, the perception is that “somehow you must be doing something that is not as good. But there’s no evidence of that at all.”