There were some pretty straightforward categories — train, plane, bike, boat ... but it didn't take long for things to get squirrelly. Do LSD trips count? (Yes!) Can we call "time" a mode of transit, or do we have to say time machine? (Eh. Still not sure. We couldn't agree.) Do the dogs and cat who travel by paw in The Incredible Journey qualify for the "by foot" list? (Sure, why not!) What do we do with James and the Giant Peach? (Create a big "miscellaneous" list, obviously.)
It wasn't always pretty, but eventually we settled on 12 lists: train, plane, car, bike, boat, foot, city transit, horse, balloon, rocketship, time and a miscellaneous category that includes drugs, dragons and giant peaches. (A moment of silence here for a fun list called "Connections" that included books featuring multiple modes of transit — like Nellie Bly's Around the World in Seventy-Two Days. Things were just getting too unwieldy, and it didn't make the cut.)
Lists, lists, lists. Oh, how I love them.