Protesters blocking border crossings between Canada and the United States risk hurting the auto industry, the White House warned on Wednesday, as Ottawa urged an end to the 13-day demonstration against coronavirus mandates.

Two Major Arteries Closed

The Ambassador Bridge, a key supply route for the U.S. auto industry in Detroit, has been shut for inbound Canada traffic since Monday night.

Another border crossing in Alberta has been closed in both directions since late on Tuesday.

Starting as a "Freedom Convoy" occupying downtown Ottawa opposing a vaccinate-or-quarantine mandate for cross-border truckers mirrored by the U.S. government, protesters have also aired grievances about a carbon tax and other legislation.

"I think it's important for everyone in Canada and the United States to understand what the impact of this blockage is on workers, on the supply chain, and that is where we're most focused," White House press secretary Jen Psaki said on Wednesday.

"We're also looking to tracking potential disruptions to U.S. agricultural exports from Michigan into Canada."

Bank of Canada Governor Tiff Macklem called for a swift resolution.

"If there were to be prolonged blockages at key entry points into Canada, that could start to have a measurable impact on economic activity in Canada," he said.

"We've already got a strained global supply chain. We don't need this."

Emergency Minister Weighs In

The protests were disrupting jobs and the economy's supply chain and "must end before further damage occurs," Canada's Emergency Preparedness Minister, Bill Blair, told reporters in a press briefing.

The bridge closure has already caused a shortage of parts at carmaker Stellantis' assembly plant in Windsor, Ontario. The company said it had to end shifts early on Tuesday, but the plant was able to resume production Wednesday morning.

The auto industry is also struggling with a lack of semi-conductor chips worldwide.

Protesters say they are peaceful, but some Ottawa residents have said they were attacked and harassed. In Toronto, streets were being blocked.

"We continue to know that science and public health rules and guidance is the best way to this pandemic is the way we're going to get to the other side," said Prime Minister Justin Trudeau.