Union Pacific Corporation (NYSE:UNP)'s Big Boy 4014, the world's largest operating steam locomotive, has been touring the country this summer, and grown adults keep tearing up when they see it. CEO Jim Vena said the tour east of the Mississippi wouldn't have been possible without one thing: the railroad operating firm's pending merger with Norfolk Southern, since Union Pacific's own tracks run west of the river. In part, the nostalgia tour is a goodwill campaign for the biggest deal in the company's histor ...