https://www.deadlinedetroit.com/articles/29860/truckers_protesting_covid_mandates_clog_traffic_on_detroit_s_ambassador_bridge

"Trafffic at the busiest border crossing in North America [is at] a virtual standstill Tuesday," The Windsor Star posts in mid-afternoon.

The Canada Border Services Agency on Tuesday afternoon declared the port of entry closed until further notice. On the Detroit side, the Michigan Department of Transportation said the bridge remained closed to Windsor-bound traffic. It advises truckers to use the Blue Water Bridge in Port Huron, 70 miles away. Passenger vehicles can use the Detroit-Windsor tunnel.

The impact is serious, as intended. "More than 25 percent of goods traded between the United States and Canada moves across the privately owned Ambassador Bridge," notes Crain's Detroit Business.
"Blockades at Canada's borders are threatening fragile supply chains already under pressure due to pandemic related shortages and backlogs," association CEO Brian Kingston said in a statement. "We are calling on cooperation from all levels of government to resolve this situation and bring an immediate end to these blockades."
Kingston called the crossing "a key conduit for motor vehicles and parts, Canada's second largest export."