Multiple blockades at some of the busiest routes linking Canada to the United States are disrupting supply chains of major car companies, leading to production stoppages and fanning alarm that protests in Canada are threatening the country’s economy and trade with the United States, its biggest trading partner.
Automakers, who are already suffering from a global shortage of semiconductors needed to power their cars, are being particularly affected by the partial shutdown of the Ambassador Bridge, which links Detroit, Mich., with Windsor, Ontario, and accounts for roughly a third of the trade between the two countries.
Trucks make thousands of trips across the bridge each day in both directions, carrying $300 million worth of goods, about a third of which are related to the automobile industry, a major employer across the Midwest and Ontario.
As the border blockades in Ontario continued, Ford Motor Company said Thursday morning that plants in Oakville and Windsor were running at reduced capacity. Toyota said the shutdown would prevent the company from being able to manufacture anything at its three Canadian plants for the rest of this week. And G.M. said it had canceled two shifts on Wednesday and Thursday at a factory in Lansing, Mich., that makes sport utility vehicles.
The blockades are a spillover from demonstrations in Canada’s capital of Ottawa, which began nearly two weeks ago when loosely organized groups of truck drivers and others converged on the city to protest vaccination requirements for truckers crossing into Canada from the United States. In addition to the blockades, the protests have morphed into a battle cry against pandemic restrictions in general and the leadership of Prime Minister Justin Trudeau.
Mr. Trudeau said on Thursday that the protests were undermining businesses, supply chains and the Canadian economy, and he reiterated his repeated call for them to end.
With protests in Ottawa and blockades in other parts of Ontario, the protests have presented a challenge to stretched law enforcement. On Wednesday night, the Ottawa police emergency line was “almost jammed” by 911 calls, a significant number of them traced to United States addresses, Peter Sloly, Ottawa’s police chief, said Thursday.
“They have command centers established here and across the country, and beyond this country,” Mr. Sloly said, referring to the fund-raising, coordination and communication among the demonstrators. “The level of capability that I’m talking about has been validated by our national security agencies.”
Drew Dilkens, the mayor of Windsor, Ontario, said Thursday that the city was seeking an injunction to end the blockade of the Ambassador Bridge.
“The individuals on site are trespassing on municipal property” he added. If necessary, they “will be removed to allow for the safe and efficient movement of goods across the border.”
Michigan’s governor, Gretchen Whitmer, on Thursday called on Canada to reopen traffic on the Ambassador Bridge. “It is imperative that Canadian, local, provincial and national governments de-escalate this economic blockade,” her statement said.
Canada’s minister of public safety, Marco Mendicino, said on Thursday that the Royal Canadian Mounted Police, the national police force, were sending additional officers to Ottawa and Windsor, and to the border crossing in Coutts, Alberta, where protests are also ongoing.
The scene in Ottawa outside the country’s seat of government remained a raucous party Thursday, with hundreds of people milling between the cabs of giant trucks parked in the middle of the street, many wearing Canada flags around their shoulders like capes.
However, there was a thinning out of protesters — with some empty spaces where trucks had been just the day before.
Far-right and anti-vaccine groups around the world have amplified the message of the Canadian protesters on social media, raising millions of dollars in online campaigns. The protests have also inspired copycat convoys in France, New Zealand and Australia. In the United States, protesters may be planning a copycat convoy near the Super Bowl in Los Angeles on Sunday, according to a Department of Homeland Security internal memo obtained by The New York Times.
Paris police officials on Thursday issued an order banning a convoy of truckers and drivers heading to the French capital to protest against the country’s vaccination pass program, as part of a movement directly inspired by Canada’s trucker-led protests.
In Canada, Mr. Trudeau has faced a barrage of criticism from opposition politicians, including the contention that overzealous restrictions are keeping Canada in a state of a permanent pandemic, and that he has been too passive in the face of the protests undermining Canada’s image on the global stage.
But in a sign of intensifying impatience with the protests, even among former political supporters, Candice Bergen, interim leader of the Conservative Party, on Thursday called for the protesters to “take down the barricades,” citing disruptions to the economy.
Constant Méheut contributed reporting.