OMAHA, Neb. & ATLANTA--(BUSINESS WIRE)--Union Pacific Corporation (NYSE: UNP) and Norfolk Southern Corporation (NYSE: NSC) today acknowledged two significant milestones in the creation of America's first transcontinental railroad, which will eliminate time-consuming interchanges between railroads and strengthen the nation's supply chain. The Surface Transportation Board (STB) has unanimously denied merger opponents' requests to dismiss the companies' revised merger application. With the rejecti.