While traffic in both directions was initially blocked, US-bound lanes have since reopened, Windsor Police tweeted.
Drivers demanding an end to federal COVID-19 vaccine mandates for cross-border traffic began blocking the streets of Canada's capital, Ottawa, on January 28.
Since Sunday night, police have started slowly taking back control, seizing thousands of litres of fuel and removing an oil tanker truck.
Ottawa Deputy Police Chief Steve Bell told reporters on Tuesday that police have immobilised many of the heavy vehicles taking part in the blockade. He said about a quarter of the 418 protest trucks in the downtown have children in them, and police are concerned for their welfare in relation to cold, noise, carbon monoxide risks and access to sanitation.
Canada's Public Safety Minister Marco Mendicino told reporters that he had been in touch with the mayor of Windsor and local legislators about the blockade at the Ambassador Bridge, connecting Detroit, Michigan, with Windsor, Ontario.
"We will continue to work so that we can keep the supply chains moving across the Ambassador Bridge, as well as the wheels of our economy turning," he said.
Canada sends 75 per cent of its exports to the US, and the bridge usually handles about 8000 trucks a day.
The owner of the bridge, the Detroit International Bridge Co, said international commerce on the bridge needed to resume.
"We encourage the appropriate officials to take prompt action to alleviate the situation as quickly as possible in a manner that reflects mutual respect," the company's chairman, Matt Moroun, said in a statement.
The president of the Canadian Vehicle Manufacturers' Association called for an immediate end to the blockade, saying "persistent delays at the Ambassador Bridge risk disrupting automotive production that employs tens of thousands of Canadians".
Canadian Prime Minister Justin Trudeau appeared in public on Monday for the first time in more than a week after being infected with COVID-19, saying the protest had to stop.
Trudeau was due to return to parliament on Tuesday to face opposition legislators demanding he do more to end what one aide called a "national humiliation."
He has denounced the demonstrators' tactics.
"Individuals are trying to blockade our economy, our democracy, and our fellow citizens' daily lives," he told an emergency debate in the House of Commons on Monday night.
"It has to stop."
But one of his Liberal Party colleagues has broken rank on the government's hardline stance on vaccine mandates. Joel Lightbound called on the government to move away from divisive politics and present a clear roadmap for lifting of pandemic restrictions.
Meanwhile some provinces are beginning to lift the strict COVID-19 restrictions.
Quebec Premier Francois Legault on Tuesday announced a gradual reopening of the province's offices, businesses, bars and social activities through March 14, while lifting restrictions on the number of visitors allowed in private homes.
Legault said a recent protest by truckers in Quebec City did not influence his plans, but acknowledged that some people in the French-language province were fed up with the restrictions.
Saskatchewan Premier Scott Moe said the requirement to provide proof of vaccination or a negative test for businesses, workplaces and other public venues will end on February 14.
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