Union Pacific wants to buy Norfolk Southern in a $85 billion deal that would create the first transcontinental railroad in the U.S, and potentially trigger a final wave of rail mergers across the country.

The $85 billion deal announced on Tuesday would create the nation's first coast-to-coast freight rail operator and reshape the movement of goods from grains to autos across the U.S., which are issues of focus for the board. Below are details of the board and what it will examine for the Union Pacific deal. What is the Surface Transportation Board?

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