Rowan mentioned above:

And did you ever get to the bottom of the "Four Colour Problem"?

Which I believe is a reference to the problem of color-coding states and provinces so that no two adjacent states have the same color, limited to only four colors, no easy problem if you are juggling 48 states. One does start in the United States where four of them meet and then try to work out in all directions. The problem used to drive cartographers crazy until they discovered how "cross-hatching" patterns or "dot" patterns could dramatically increase the options. They then slept like babies for generations. Now, of course, there are new countries every year and their delight and frsutration is that their work will never be complete!

One of our favorite tests for geography students would be to present them a well known outline of a region of the world "upside down" and ask them to identify where it was. Oh, what fun we used to have driving students crazy!

Cheerily,
Charley Noble