North Platte, Neb; $6; up.com
At 2,850 acres, this “factory” is too large (and too dangerous) for a walking tour. However if you take the elevator to the eighth floor at the visitor center of the massive Union Pacific Railroad’s Bailey Yard in North Platte, Neb., you can watch as 14,000 railroad cars are “sorted” every 24 hours. This is the largest “hump” yard in the world, a name derived from the mounds the remotely controlled railroad cars ascend before rolling onto one of 114 tracks where they will couple with other railroad cars to form a train heading east or west.
The eighth-floor observation deck gives an inside, air-conditioned panoramic view of the activity, while the open-air seventh floor observation deck allows visitors to listen to the diesel engines and the box cars clang as they are joined together.