Union Pacific is seeking to buy Norfolk Southern in a $85 billion deal that would create the first transcontinental railroad in the U.S.

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

Union Pacific Corp. agreed to acquire Norfolk Southern Corp. in a $72 billion cash-and-stock transaction, forming the only US transcontinental railroad in what stands to be the industry’s largest deal ever.