"Basically, if there's a shutdown of transportation routes, the auto industry comes to a screeching halt in about two days," Robert Wildeboer, executive chairman of Martinrea International Inc., said Tuesday on BNN Bloomberg Television.

Martinrea is a major auto parts manufacturer based in Vaughan, Ontario. It manufactures engine blocks, transmissions, cases, housings, suspensions, chassis components, and body paneling for automotive companies in Detroit. 

"We have 38 trucks cross at the Detroit border per day and 16 in Sarnia," Wildeboer said. Since protesters have shuttered the border crossing, it appears Martinrea's ability to cross into Detroit has become challenging.