Union Pacific , the largest U.S. freight railroad operator, is exploring a possible acquisition of Norfolk Southern to create a $200 billion coast-to-coast rail network, a person familiar with the matter said.

Union Pacific is in talks to merge with Norfolk Southern, The Wall Street Journal reported Thursday, in a deal that would shake up the railroad business in America. The Journal cited people familiar with the matter.

Merger talk is swirling around Union Pacific Corp. and Norfolk Southern Corp., in a deal that could create a railroad mega-carrier and a huge transcontinental network spanning the U.S.