When my teenage daughter skipped town to hop trains, I was drawn into the secret world of the railroads.  My search for why she would be attracted to this life had me hanging out in train yards, talking to hobos and rail workers, and even making a lame attempt to hop a train. That quest is the subject of City of the Rails, which reveals an underground world with its own citizens, rules, laws and law enforcement. This rich world, filled with astonishing characters, hides in plain sight in every city in the nation. The podcast captured a huge audience that resonated with that American urge to just go, leave it all behind, and let someone else figure out why you split. People got hooked, and spread the word, earning the show more than a million downloads.