Steam Bison being vaguely in a desert in the united states means he's actually fairly close to California, so Luke could probably visit Phoenix if he had the time between all the puzzle solving. (Assuming of course that they aren't going to make up a new desert in the US like they did for Miracle Mask with Monte d'Or being able to be driven to from London)
i don't know enough about the geography of the Southwestern states to make a guess at which states Steam Bison could be in based on it looking like a plateau that Layton and Luke are standing on there, so ppl more familiar with those states have a go at it!
teamgayotix