Police have started to clear a blockade of the main crossing between Canada and the United States.
After days of protests by truckers against Covid rules at the Ambassador Bridge in Ontario, officers urged them to heed an injunction against the demonstration.
The vital trade route links Windsor, Ontario, with Detroit, Michigan.
Truckers’ protests against Covid vaccine mandates are also ongoing at other border crossings and in Ottawa.
Friday’s court order was filed by the city of Windsor and the Automotive Parts Manufacturers’ Association, which argued that they were losing as much as $50m ($39m; £29m) per day because of the convoy.
Following the injunction, Windsor Police put out a statement to “make demonstrators clearly aware that it is a criminal offence” to block the border crossing. The police added that a criminal conviction could lead to the seizure of vehicles and the inability to enter the US.
But hours later, crowds of people waving Canadian flags flouted the order and continued to occupy the bridge.
Police added on Saturday: “We urge all demonstrators to act lawfully [and] peacefully. Commuters are still being asked to avoid the areas affected by the demonstrations at this time.”
Hundreds of other protesters continue to demonstrate in the centre of Ottawa, the nation’s capital. Two other border crossings with the US are also being blocked by anti vaccine mandate protesters.
Prime Minister Justin Trudeau spoke with US President Joe Biden about the border blockades on Friday.