After back-to-back train disasters, regulators approve the largest rail merger in decades creating a line that would stretch from Canada to Mexico

• Regulators approved a railroad merger that would create a single route stretching from Canada to Mexico.
• The rail industry has seen train accidents and labor disputes in recent months.
• Nonetheless, regulators argue the merger will improve safety and competition in the US economy. 

Rail consolidation has a terrible track record, but regulators think this time it will be different.