OMAHA, NEBRASKA, US — Union Pacific Corp. has agreed to acquire Norfolk Southern Corp. for $85 billion, a merger that would unite two of North America’s Class I freight railroads and major US-based grain shippers to create the country’s first transcontinental railroad.

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.