In the book, Mt. Crumpit doesn't just function as a place. It's also the apex of the story. It is here, on this peak, at the highest of heights, that the Grinch is torn between two sides.
Will he pick evil and push the sled full of toys and holiday cheer over the side of the mountain? Or will he pick good and drag the sled back down to Who-ville?
Mt. Crumpit represents struggle, and it represents real change for the Grinch. For more on this, see our section on "Setting."