Every day more than $4 billion worth of goods cross the United States’ borders with Canada and Mexico – U.S. auto parts headed for car factories in northern Mexico, cartons of Mexican avocados bound for California supermarkets, Canadian aluminum destined to become cans of Campbell Soup.

To President Donald Trump, America’s trade relationship with Mexico was intolerable.

Workers at a General Motors plant in Mexico have voted to end a collective bargaining contract negotiated by an old guard union accused of intimidation tactics in earlier votes.