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.

Stagnant volumes that have shifted to the trucking sector over the years appear to support the arguments for railroad consolidation.

Union Pacific offers $20 billion cash and one share of its stock to buy Norfolk Southern Tuesday in a merger that could trigger the final wave of railroad mergers across the country