The merger would create the United States’ first coast-to-coast rail network, spanning 50,000 miles and 43 states.

Union Pacific said on July 29 that it had agreed to buy smaller rival Norfolk Southern for $85 billion, including debt, in a deal that would create the first transcontinental U.S. railroad.

The $85 billion deal announced on Tuesday would create the nation's first coast-to-coast freight rail operator and reshape the movement of goods from grains to autos across the U.S., which are issues ...