Americans are making too many solo dinner reservations.

That was one takeaway from the annual World Happiness Report, which was released on Thursday and showed that the United States had dipped to its lowest slot in the country rankings — 24th — after being ranked as high as 11th in 2012, the first year of the report.

Americans are increasingly miserable, the report says, and it explored a possible indicator: The number of Americans eating alone has risen exponentially this century.

In 2023, according to data from the Bureau of Labor Statistics’s American Time Use Survey, about a quarter of Americans reported eating all of their meals alone the previous day, an increase of 53 percent since 2003.

“The extent to which you share meals is predictive of the social support you have, the pro-social behaviors you exhibit and the trust you have in others,” Jan-Emmanuel De Neve, a University of Oxford professor and an author of the report, said in an interview.

This trend is even more pronounced among young people. For American adults under 25, there has been an 80 percent increase in dining alone among Americans, numbers that Dr. De Neve called “disconcerting.” The survey, which is compiled annually by a consortium of groups including the United Nations and Gallup, offers another data point in the so-called loneliness epidemic, which researchers and officials have said in recent years is becoming a bigger concern, particularly among young men as they spend more and more time on their phones.

Eating alone increases political polarization as well, Dr. De Neve said.

“The fact that we’re increasingly socially isolated means also that we’re not testing our ideas about the world with other people,” he said. “And the more you sit around the table with other people who might have somewhat different views, the more you start moderating your own views. And the increasing lack of social interaction and social isolation as a result, for a lot of people — amplified by echo chambers — makes people more radical.”

The report also makes the case that declining happiness and social trust in the United States and parts of Europe has driven a series of “anti-system” political victories, such as the election of President Trump, and a rise in political polarization. According to the study, the share of American people who trust others has declined by almost half since the 1970s, dropping to 30 percent from 50 percent.

“Far-left voters have a higher level of social trust, while right-wing populists have a very low level of social trust,” the report says.

For the eighth year in a row, Finland took the top spot in the rankings. Of course, not everyone in Finland is happy with the survey, which essentially asks residents of countries to rate their own happiness. The study accounts for the last three years.

On Thursday, during a panel discussion about the report in Washington, D.C., Leena-Kaisa Mikkola, Finland’s ambassador to the United States, offered several theories for why the Finns have been so happy for so long. They included trust among fellow citizens and in the educational system, proximity to nature and “weekly sauna sessions.”

“Our American friends, you smile and laugh much more than we do,” Ms. Mikkola said during the panel discussion, which was hosted by the digital news outlet Semafor. “But happiness for us is maybe being content.”

In an interview, Ms. Mikkola said Finland had other structural advantages over the United States, including its size.

“In a small country, there is also perhaps more of this awareness that we need each other,” she said. “In a bigger country, you can somehow box yourself into different corners.”

Costa Rica (No. 6) and Mexico (No. 10) entered the Top 10 for the first time, and other countries like Lithuania (16th, up from 19th) and Slovenia (19th, up from 21st) continued to move up in the rankings.

During the panel discussion, Catalina Crespo Sancho, Costa Rica’s ambassador to the United States, likened her country’s population to sloths — in a good way.

“They’re very slow, yes. But nobody wants to eat them,” Ms. Sancho said. “They do not want to eat anyone or any of the other animals in the forest. They get along with everyone. All the animals get along with them. However, they get to where they need to get, even though it takes forever to cross a road.”

But as far as the United States is concerned, Ms. Mikkola remained optimistic: “I haven’t met an unpleasant person during my six months here.”

Elon Musk has said that “Canada is not a real country,” just one of his social media jabs at the U.S. neighbor.

But people in Canada have done real damage to the vehicles and dealerships belonging to his electric car company, Tesla, according to the police.

More than 80 Teslas had their tires punctured and bodies scratched at a lot in Hamilton, Ontario, the police said on Thursday. Several acts of vandalism against Tesla property have also been committed in the United States.

Hamilton, west of Toronto, is the heart of Canada’s steel manufacturing industry and a battlefront in the country’s trade war with the United States.

President Trump has imposed tariffs on steel and other Canadian products and Canada has responded by applying levies to $20.5 billion worth of exports from the United States.

Mr. Trump has also claimed that Canada has long “ripped off” the United States and wants to make it the 51st state.

Canadians have responded with a grass-roots protest, changing how they shop, travel and think about their relationship with the United States, the country’s closest ally and trading partner. Even the cherished Canadian hockey legend Wayne Gretzky is not immune from the fury for his silence on actions taken by Mr. Trump, who is a friend.

Canadian provincial leaders have introduced their own measures to retaliate against the tariffs, including removing American alcohol products from liquor stores and barring U.S. companies from applying for procurement contracts.

Canadians have also directed their ire at Mr. Musk, the billionaire businessman, who is helping lead Mr. Trump’s effort to reshape the federal government.

In Montreal, two members of a climate advocacy group called Last Generation Canada doused the exterior of a Tesla dealership in pink spray paint on Wednesday, according to a statement issued by the group.

The group said it had committed the act because it believed that Mr. Musk was “destroying democracies and spreading climate denial.”

The two members involved in the episode were later arrested, the authorities said.

Concerns about vandalism and protests led organizers of a recent auto show in Vancouver to exclude Tesla from the event.

“This decision will ensure all attendees can be solely focused on enjoying the many positive elements of the event,” Eric Nicholl, the show’s executive director, said in a statement.

Tesla dealerships in other Canadian cities, including Ottawa, the capital, have attracted angry protesters carrying signs.

Ontario, Canada’s most populous province, canceled a contract worth 100 million Canadian dollars, about $70 million, with Starlink, the satellite internet company owned by Mr. Musk.

Last month, thousands of Canadians called on the government to revoke Mr. Musk’s Canadian citizenship and passport in a petition that now has about 376,000 signatures.

A French scientist was prevented from entering the United States this month because of an opinion he expressed about the Trump administration’s policies on academic research, according to the French government.

Philippe Baptiste, France’s minister for higher education and research, described the move as worrying.

“Freedom of opinion, free research and academic freedom are values we will continue to proudly uphold,” Mr. Baptiste said in a statement. “I will defend the possibility for all French researchers to be faithful to them, in compliance with the law, wherever they may be in the world.”

Mr. Baptiste did not identify the scientist who was turned away but said that the academic was working for France’s publicly funded National Center for Scientific Research and had been traveling to a conference near Houston when border officials stopped him.

The U.S. authorities denied entry to the scientist and then deported him because his phone contained message exchanges with colleagues and friends in which he expressed his “personal opinion” on the Trump administration’s science policies, Mr. Baptiste said.

It was not immediately clear what led the border authorities to stop the scientist, why they examined the contents of his phone or what they found objectionable about the conversations.

Customs officers are allowed to search the cellphone, computer, camera or any other electronic device of any travelers crossing the border, according to U.S. Customs and Border Protection, although the agency says that such instances are rare. In 2024, less than 0.01 percent of arriving international travelers had their electronic devices searched, according to the agency.

Mr. Baptiste’s office declined to provide further details about the case. A spokesman for the American Embassy in Paris also declined to comment.

A spokeswoman for the National Center for Scientific Research said that the scientist who was turned back did not wish to speak to the media and declined to comment further.

The Agence France-Presse news agency reported earlier on the scientist’s refused entry to the United States.

Mr. Baptiste, the minister, has been particularly vocal over the past few weeks in denouncing threats to academic freedom in the United States, where funding cuts and layoffs by the Trump administration have targeted institutions of higher education, scientific research and the federal government’s own scientific work force.

Mr. Baptiste has urged French universities and research institutes to welcome researchers seeking to leave the United States.

“Europe must be there to protect research and welcome the talent that can contribute to its success,” Mr. Baptiste wrote on social media after meeting with his European counterparts in Warsaw on Wednesday to address “threats to free research in the United States.”

Jennifer Jones, the director of the Center for Science and Democracy at the Union of Concerned Scientists, an advocacy group in the United States, said she worried that cases like the one involving the French scientist would have a chilling effect on research collaboration across borders.

“My fear is that these are early cases with many more to follow,” Dr. Jones said. “I am hearing from my network that people are very concerned about any kind of international travel in either direction.”

“And that should worry all of us,” she added. If scientists limit their movements to conferences and other events designed to advance research, she said, “it is the public that is going to suffer.”

Ségolène Le Stradic contributed reporting.

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Snow plows rumbled and salt trucks spewed de-icing pellets onto Toronto’s streets, barely visible under two feet of snow. A stocky man brandished a comically small red shovel as he helped dig out a car trapped at an intersection.

The helping hand was provided by Doug Ford, the premier of Ontario, Canada’s most populous province and its largest economy, who came to the rescue of drivers trapped in the January 2022 snowstorm, even giving a few of them rides home.

Some residents criticized the gesture as having the patina of a public relations stunt, but the “little red shovel” moment captured Mr. Ford’s essence: the Everyman who, despite lacking some of the polish of other politicians, still gets the job done.

Mr. Ford has lately been leading the charge against a different kind of storm that has rolled into Canada: President Trump’s threats to the country’s economy and his desire to make it the 51st state.

Mr. Ford, 60, has thrust himself into the public spotlight, aggressively defending Canada’s sovereignty, economy and honor, earning him the moniker “Captain Canada” among some Canadians at a moment when the country feels betrayed by the United States and has responded with fury.

“It’s like a family member stabbing you right in the heart,” Mr. Ford told reporters after Mr. Trump began threatening tariffs on Canada. The premier has taken to wearing a “Canada Is Not For Sale” baseball cap and a “Never 51” hockey jersey, both alluding to Mr. Trump’s repeated statehood declarations.

He has pulled American alcohol off liquor store shelves — Ontario is one of the largest buyers of U.S. spirits — and canceled the government’s contract with Starlink, an internet company owned by Elon Musk, Mr. Trump’s billionaire ally.

Mr. Ford, whose office said he was unavailable for an interview, also briefly imposed a 25 percent surcharge on the electricity that Ontario supplies to Michigan, Minnesota and New York.

Those tactics have caught Mr. Trump’s attention.

“There’s a very strong man in Canada,” Mr. Trump told reporters last week, referring to Mr. Ford, who retreated on the surcharge after speaking with Trump administration officials who offered to meet their Canadian counterparts to discuss the tariff standoff.

Mr. Ford, the leader of the Progressive Conservative Party of Ontario, ended up joining a small delegation of Canadian government officials who traveled to Washington last week to discuss the trade battle at the White House.

Still, Mr. Trump is expected to hit Canada with another round of tariffs on April 2. Canada has already retaliated against earlier tariffs with levies on $20.5 billion worth of U.S. goods.

Tariffs could push Canada’s economy into a recession, and already a handful of Canadian metal and manufacturing companies have announced dozens of layoffs in response to the trade war.

“If we go into a recession, it’s self-made by one person,” Mr. Ford said during an interview for American television, where he has become a regular presence on Fox News and MSNBC, among other networks. “It’s called President Trump’s recession.”

Ontario has spent millions in advertising dollars on commercials broadcast to an American audience highlighting the ties between the two countries and warning of the pain that tariffs on Canada would cause to their pocketbooks.

Canada has long seen itself as being in the United States’ shadow, but Mr. Trump’s aggressive campaign, including constant grievances that Canada takes financial advantage of the United States, has ignited a newfound sense of pride and a recognition of its role on the world stage.

“I am feeling incredibly patriotic, incredibly driven to protect what I know we have,” said Arlene Dickinson, a Canadian investor, television personality and member of a federal trade advisory group.

She credits Mr. Ford for loudly projecting that sentiment.

“He hasn’t wavered,” Ms. Dickinson said. “He hasn’t put individual interests ahead of the whole country’s interests.”

The trade war has come at a moment of upheaval in Canadian politics. Justin Trudeau, Canada’s recently departed prime minister, has been succeeded by Mark Carney, a former central banker, who is soon expected to call a national election that will pit his party, the Liberals, against the Conservatives.

With Canada’s top political leadership position in transition, Mr. Ford has been seen as a stand-in representative for the country. He capitalized on his popularity by calling a provincial election more than a year early and handily won a majority.

Dennis Pilon, a politics professor at York University in Toronto, said rushing the Ontario election helped Mr. Ford keep the momentum and eyes on him.

“He did that precisely to prevent the narrative from shifting anywhere else,” Mr. Pilon said.

Before becoming Ontario’s premier in 2018, Mr. Ford was elected in 2010 to the Toronto City Council, bolstered by voters known as “Ford Nation” who had also supported Mr. Ford’s brother, Rob Ford. He was a former Toronto mayor who died from cancer in 2016 and whose turbulent political career ended after he confessed to smoking crack cocaine.

Mr. Ford’s high-profile role in Canada’s standoff with the United States has blurred some of the controversies dogging him back home, including a plan to convert waterfront parkland in Toronto into a spa.

The authorities are also investigating opaque real estate deals brokered by his government to make tracts of environmentally protected land available to developers.

And he has faced backlash over his plan to address Toronto’s notorious traffic problems by tearing out popular bike lanes.

But Mr. Ford remains sought out for his thoughts on Canada’s main challenge abroad, telling reporters this week that Mr. Trump’s annexation threats were a compliment.

“We’ll never be a 51st state,” he said. “Canada is not for sale. But isn’t it nice that someone thinks we have the greatest country in the world?”