Computer problems at U.S. Customs and Border Protection snarled traffic for hours leading to the Ambassador Bridge and the Blue Water Bridge.
The glitch started causing problems Tuesday morning. Traffic backed up along Huron Church Road to Highway 401 in Windsor and Highway 402 in Sarnia.
Traffic began moving better by late afternoon.
Border officials still processed travellers throughout the day, but at a slow rate.
“We understand the frustration and are doubling our efforts to restore everything to normal,” said Ken Hammond, chief CBP officer and public affairs liaison, at the height of the problem.
Windsor police and OPP officers were telling drivers to avoid the area if possible.
The Windsor Detroit Tunnel experienced fairly high volumes Tuesday morning, but traffic was not too backed up by the afternoon, according to a tunnel spokesperson.