A strike by Canadian railway workers threatens to slow or shut down production at some U.S. auto plants.
5,000 Canadian Pacific Railway workers walked off the job early Wednesday because of a dispute with management over a new contract.
Large numbers of finished vehicles and auto parts come to U.S. factories via Canadian Pacific.
Ford and General Motors say they don't expect the strike to affect production - at this time.
Chrysler says it is actively working to mitigate any impact to its operations through alternative shipment methods, such as trucks.
The longer the strike goes, the greater the chance it could affect the U.S. auto industry. The Canadian Labor Ministry says it has the authority to intervene and will do that if the two sides haven't reached a deal by Monday.