The moment it dawned on Thomas Fullagar that his job search was not going well came in April, about six months into the process, when he applied for a position in Manhattan, Kan.

The job, at a technology company called CivicPlus, involved relatively straightforward data analysis that he wouldn’t strain to do. In fact, he had done much more complicated work while completing his Ph.D. in economics at the University of California, Santa Barbara. Further improving his odds, he had grown up in Manhattan, the home of Kansas State University, and his mother knew someone at the company, who helped fast-track his application.

Yet despite his connections and credentials, he did not get the job. He didn’t even get a second interview. “It was in Manhattan, Kansas — who the heck is applying for this?” Dr. Fullagar, 33, wondered. “That one was really baffling.”

For decades, earning a Ph.D. in economics has been a nearly foolproof path to a lucrative career. Even as bearers of advanced degrees in history, English or anthropology struggled to find gainful employment, the popularity of economics as an undergraduate major created plenty of tenure-track teaching positions, while government agencies snatched up Ph.D. economists in bulk. Those looking for even larger paychecks could turn to tech companies, Wall Street and consulting firms, which bid up the price of economists as if they were a bespoke cryptocurrency.

Last year, the average base salary for newly hired economics professors at major research universities was more than $150,000, according to the American Economic Association, and their compensation swelled to about $200,000 once bonuses and summer teaching were included. As recently as the 2023-24 academic year, the employment rate for Ph.D. economists within a few months of graduation was 100 percent, said John Cawley, the chair of the association’s Committee on the Job Market, citing the group’s surveys. Job satisfaction topped 85 percent.

Those glory days seem to be ending. Universities and nonprofits have scaled back hiring amid declining state budgets and federal funding cuts. At the same time, the Trump administration has laid off government economists and frozen hiring for new ones.

Tech companies also have grown stingier, and their need for high-level economists — once seemingly insatiable — has waned. Other firms have slowed hiring in response to the economic uncertainty introduced by President Trump’s tariffs and the possibility that artificial intelligence will replace their workers, even if those workers have a doctoral degree.

“The advent of A.I. is also impacting the market for high-skilled labor,” said Betsey Stevenson, a labor economist at the University of Michigan, in an email. “So the whole thing is kind of a mess.”

Of course, if it were only some egghead economists scrambling to find work, that might be not be terribly consequential. But the same forces bedeviling economists are crimping employment for other highly trained scientists and social scientists, as well as for many recent college graduates, whose jobless rate has been unusually high for an otherwise strong economy.

The drop in government payrolls and federal funding for universities and nonprofits alone is a major problem, since they support two to three times as many jobs for college graduates as for those without degrees. In some cases, workers with Ph.D.s are displacing others with master’s or bachelor’s degrees.

Then there is the potential impact on the country’s future. Marcia McNutt, a geophysicist who is president of the National Academy of Sciences, said a sharp drop in the number of research jobs in the hard sciences and social sciences would send Ph.D.s abroad. Their flight will deprive the government of the brainpower it needs to perform basic functions and leave U.S. firms less innovative and competitive.

“U.S. industry is incredibly dependent on the training that is done in colleges and universities,” Dr. McNutt said. “When the top people go elsewhere, we’ll be left with the B team in America.”

Squeezing From Top to Bottom

Dr. Fullagar and his classmates were anxious about their prospects even before the Trump administration started threatening federal funding. After a few shaky pandemic years, hiring had recovered in 2022. But by the 2023 academic year, the market was wobbly again — about 20 percent fewer positions advertised on the main American Economic Association jobs board — as tech companies and universities shifted into austerity mode.

Longer-term trends may have also taken a toll. Universities have relied more and more on instructors and other nontenure-track faculty to teach undergraduates in recent decades. In some cases, the tenured ranks have become clogged by baby boomers putting off retirement.

The University of California, Santa Barbara, typically produces 10 to 15 Ph.D. economists a year, and about one-third to half of them secure tenure-track academic jobs right away, said Daniel Martin, an economics professor and the graduate program’s job placement officer. A few more typically land jobs at federal or international agencies.

But Dr. Martin was so pessimistic heading into the last academic year that he started recommending that doctoral candidates consider other options. He even urged them to think about a summer internship at a company, advising them that “industry jobs are not something that just come to you anymore — you have to aggressively pursue them.”

The pessimism proved warranted. At Harvard, Lawrence Katz, a prominent labor economist, had seven students seek tenure-track academic positions; only three got them. The rest took private-sector jobs or prestigious postdoctoral fellowships that will require them to go back on the job market in a year or two.

It’s not exactly panhandling, but a sharp departure from only a few years earlier. Just before the pandemic, essentially “all of those who wanted academic jobs would have gotten them,” Dr. Katz said.

The lack of top-tier jobs created knock-on effects. Victoria Wang, a recent Ph.D. candidate at the University of California, Los Angeles, another eminent department, said the finalists for an assistant economics professor position in the university’s public policy school were already assistant professors or postdoctoral fellows at other schools.

“There was no one that was straight out of a Ph.D. program,” Dr. Wang said. She avoided attending job-seeking presentations by these candidates while on the job market herself because “it stressed me out.” (She was thrilled to land a tenure-track position at Wellesley College in Massachusetts, after sending out 386 applications.)

And as recent graduates from the highest-ranked programs claimed a shrinking number of coveted positions, students from solid but not elite programs struggled even more.

At the University of Illinois Chicago, two of the six Ph.D.s on the job market this past year took jobs in state government. Those were somewhat unusual landing spots for graduates of the program because they tend to offer fewer research opportunities and “lower pay, less prestige,” said Marcus Casey, an economics professor at the school.

‘A Brutal Moment’

Dr. Fullagar had decided to focus on government and private-sector jobs. Prominent economic consulting firms typically offer incoming Ph.D. economists around $200,000 a year, and they had traditionally recruited aggressively at Santa Barbara. But those firms interviewed fewer of his classmates last fall.

“That was the first indication,” Dr. Fullagar said. He got only two bites from consultancies. They did not pan out.

Then in January, Mr. Trump took office and put the kibosh on federal hiring. Hundreds of prospective jobs vaporized overnight, including more than a dozen that Dr. Fullagar had applied for at agencies like the Treasury Department and the Census Bureau.

“That was a brutal moment,” said Dr. Martin, the placement officer at Santa Barbara. “I contacted our department and said, ‘Listen, I need to prepare you for the possibility that we may be graduating people without jobs” — something that hadn’t happened in recent memory.

In March, Dr. Fullagar thought he found a lifeline. An economist at West Virginia University advertised two postdoctoral positions, and her social media posts suggested that she was getting desperate.

“Any time someone says, ‘Email me,’ and it’s not an automated process, you’re more hopeful,” Dr. Fullagar said.

But when he applied, he got back a generic email citing a “high volume” of interest. He did not make the cut.

Dr. McNutt of the National Academy of Sciences said research by social scientists helped the government answer high-stakes questions like what motivates soldiers to defend their country and what policies encourage people to seek health care. In the private sector, the research of scientists and social scientists would be narrower and not necessarily shared with the public.

“Industry generally does research to advance a road map,” said L. Rafael Reif, a former president of the Massachusetts Institute of Technology. “The research of universities creates new road maps, new avenues.” He said it was especially important to have academic economists and other social scientists think through the societal implications of A.I.

Dr. Martin, the placement officer, said he was still optimistic about the future of the economics profession, partly because the job recession was only a slowdown relative to the highly auspicious employment climate that reigned for decades.

“Who has that?” he said. “Not even computer science has been able to place people just at will.”

Still, he acknowledged that it was “not comfortable to be at end of boom.” He said the coming academic year — the first full one in the second Trump term — could be considerably worse.

Dr. Fullagar said he was staying positive. In late July, a state government made him an offer that he was ambivalent about taking, and he held out hope that an upcoming interview at a prominent tech company would lead to something. For the moment, he had the run of a subsidized apartment in Santa Barbara.

“My lease ends in August,” he said. “If I have to move back home, then that will suck. But at this point, I’m not panicking.”