Every year, Americans buy tens of millions of Christmas trees. But decorative evergreens don't just magically show up on corner lots, waiting to find a home in your living room. There are a bunch of fascinating steps that determine exactly how many Christmas trees get sold, and how expensive they are. On this episode of Planet Money, NPR's Nick Fountain and Robert Smith visit the world's largest auction of Christmas trees — and then see how much green New Yorkers are willing to throw down for some greenery. Listen to more episodes of Planet Money on Apple Podcasts or Spotify.