Protesters blocked northbound and southbound traffic near the Coutts border in southern Alberta on Saturday afternoon, according to RCMP.
Police issued notices and asked drivers not to travel south on Highway 4 near the weighing station.
U.S. officials told northbound traffic to avoid the area as well.
Protesters also blocked access to the town of Coutts, meaning emergency vehicles could not enter or leave the area.
RCMP continued the dialogue, hoping to involve the protesters in moving their vehicles, and exploring all options, including enforcement.
Mounties said hundreds of vehicles were taking part in the protest, which was peaceful.
With files from The Canadian Press
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