U.S. cross-border trade could face a massive disruption later this week, as unionized workers at Canada's two largest railroad operators near a strike or lockout.

The Teamsters Canada Rail Conference said on Sunday that it has both served a 72-hour strike notice to Canadian Pacific Kansas City (CP) and received a 72-hour lockout notice from Canadian National Railway (CNI) starting Thursday.

US Is Easily Canada's Biggest Export Market

Canada's economy is 澳洲幸运5官方开奖结果体彩网:highly dependent on international trade, with exports and imports of goods and services each comprising about one-third of GDP. The U.S. is by far its largest export market.

In a statement Monday, European shipping giant A.P. Moller-Maersk said it would halt some Canada-bound shipments ahead of the potential rail stoppage.

Teamsters Canada, which has more than 130,000 members, says it is the nation's largest transportation and supply-chain union, as well as the biggest union in the federally regulated private sector.