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

Union Pacific and Norfolk Southern said on Tuesday that they have agreed to a merger to create a $200 billion rail giant based on their current market capitalizations.

The blockbuster deal raises the odds that Buffett’s Berkshire Hathaway, which owns the Burlington Northern Santa Fe railroad, will reach a deal with CSX to create a second transcontinental railroad. Union Pacific and BNSF compete in the western U.S., while CSX and Norfolk Southern are the two big Eastern railroads.