The American economy slowed at the end of 2018 — and there could be a further slowdown to come.

Gross domestic product — the broadest measure of goods and services produced in the United States — grew at a 2.6 percent annual rate in the final three months of last year, the Commerce Department said Thursday. That marks a significant slowdown from the middle of the year, when a sugar high fueled by tax cuts and government spending increases briefly pushed growth above 4 percent.

This year seems to be starting at an even slower pace. Many economists expect growth to drop below 2 percent in the first quarter, in part because of the partial government shutdown, which began in December and extended through most of January.

It is important to keep the cooling economy in perspective. The fourth-quarter slowdown was not as severe as many forecasters had feared, and even with the loss of momentum late in the year, 2018 as a whole was among the best years of the decadelong recovery from the Great Recession. Most economists do not expect a recession this year, putting current expansion on track to become the longest on record.

“I think this is a slowing,” said Lewis Alexander, chief U.S. economist for Nomura. “I don’t think this is ‘we’re falling into an abyss.’”

A strong year — but how strong?

Thursday’s report did give President Donald Trump some bragging rights — albeit with an asterisk.

Economic output rose 3.1 percent in the fourth quarter from a year earlier. That is a politically salient benchmark because Trump and his advisers have repeatedly promised growth of 3 percent or better, something his predecessor never achieved over a full calendar year. Trump has at other times promised growth of 4 percent or more.

“A year of 3.1 percent growth is something many people thought was impossible as recently as 2016, so it’s a major accomplishment,” said Kevin Hassett, chairman of Trump’s Council of Economic Advisers. “And it’s an accomplishment that has disproportionately benefited low-wage and blue-collar workers.”

Still, Trump didn’t quite score a clear victory. By another commonly used method of calculating annual growth — which looks at GDP over full years, not just comparing the fourth quarter of each year — the economy fell just short of that mark, coming in at 2.9 percent.

Whether growth hits 3 percent might matter politically, but it makes little difference economically. The difference between 2.9 percent and 3 percent growth is negligible in any one year, and, in any case, the Commerce Department will revise its fourth-quarter estimate in March.

The White House expects the roughly 3 percent pace of growth to continue in 2019 and for years into the future. Few independent economists agree. With the effects of the tax cuts and spending increases fading, the Federal Reserve expects growth to slow to 2.3 percent in 2019, and many economists are even more pessimistic.

Slower, but not slow

The fourth-quarter slowdown was not as bad as some forecasters had expected. Consumer spending, the bedrock of the economy, rose at a 2.6 percent rate — slower than in the middle of the year, but hardly a collapse. Exports, which slumped in the third quarter, rebounded in the fourth, suggesting that the cooling global economy is not yet dragging down American exporters. And businesses stepped up their investment in equipment, software and research, a sign that they are still betting on the future.

Still, uncertainty about the direction of the economy has made some businesses more cautious. George Whittier, who oversees operations for the Morey Corp., a manufacturer outside Chicago, said business was strong in 2018 but began to slow at the end of the year. He shrugged off weakness in December as a seasonal blip. But then January was softer and February was softer still.

Morey, which makes electronic components for cars, medical devices and other uses, has been hit by Trump’s tariffs, which raised prices on imported parts from China. At first, the impact was small, but it has grown as suppliers draw down inventories and are forced to import more.

“As each month has gone by, it has seemed like more and more components have been affected,” Whittier said.

For now, Whittier remains optimistic that the trade tensions will be resolved and 2019 will prove to be a good year. But he is taking a wait-and-see approach when it comes to making big investments.

The stimulus effects are fading

Thursday’s report left little doubt that the midyear surge in growth has dissipated, just as many economists predicted at the time. Tax cuts and federal spending increases provided a temporary lift, but that was offset by higher interest rates, trade tensions and a slowing global economy.

The effects of the stimulus will fade further in 2019.

Residential investment, a proxy for housing construction, fell for the fourth straight quarter, as higher interest rates and declining affordability weighed on construction and sales. Retail sales dropped unexpectedly in December, which could be a sign that consumers are starting to pull back. And growth in the fourth quarter was driven in part by companies building up inventories, which could reverse in 2019.

“On the one hand, I was encouraged that there wasn’t as much of a slowing as I thought,” said Ben Herzon, an economist at Macroeconomic Advisers, a forecasting firm. “But on the other hand, what propped up growth in the fourth quarter was unsustainable.”

The government shutdown came too late to make much difference to the fourth quarter, but it could be a significant drag on growth early in the year. The funding lapse idled hundreds of thousands of federal workers, left hundreds of thousands more working without pay and disrupted air travel, among other effects. Consumer confidence plummeted. Macroeconomic Advisers on Thursday cut its estimate of growth in the current quarter to 1.1 percent.

Growth that weak would leave the United States with little buffer against an unexpected round of bad news — an escalation in the trade war with China, for example, or another round of fiscal gamesmanship around the debt ceiling. A rising share of economists expect a recession in 2020 if not sooner.

“The economy’s already slowing and there are a bunch of reasons why it could slow down even more, and that just makes you vulnerable,” said Alexander of Nomura. “It would take less of a shock to push you over the edge” into a recession.

Is there reason for optimism?

Not everyone is so pessimistic. Most economists believe the shutdown did little long-term damage to the economy. Consumer confidence rebounded in February as federal workers returned to work and the stock market bounced back from its December slump. Job growth never suffered.

“The fears of the economic expansion’s demise seem to have been greatly exaggerated,” said Beth Ann Bovino, chief U.S. economist for Standard & Poor’s Ratings Services. She called Thursday’s report promising and said it suggested the economy entered 2019 on firmer footing than some economists had feared.

There are other reasons to think the economy could prove resilient. Trade tensions with China seem to have eased somewhat in recent weeks. The Federal Reserve has backed off plans to raise interest rates. And the combination of low unemployment, rising wages and low oil prices should help drive consumer spending.

“All the fundamentals are there for a solid consumer recovery,” said Michael Pearce of Capital Economics.