Union Pacific's proposed purchase of smaller rival rail operator Norfolk Southern will need to be approved by the Surface Transportation Board in Washington, an independent federal agency that oversees competition and other areas of importance in the rail industry.

Union Pacific acquires Norfolk Southern, forming the first U.S. transcontinental railroad. Read the latest stock analysis on the merger here.

Union Pacific is seeking to buy Norfolk Southern in a $85 billion deal that would create the first transcontinental railroad in the U