Take your new, unfolded map and lay it facedown on a table, with the top away from you.
Fold the top down to meet the bottom and make a good, sharp crease. The top of the map should now be faceup - but upside down - on the side nearest you.
Fold the top edge back up to the crease you made in step 2.
Flip the map over (avoid rotating), and fold the other edge up to the step 2 crease. You should now be left with a long, thin rectangle, folded accordion-style.
Rotate the map so that one of the skinny ends is away from you. Fold the top skinny end down to meet the bottom skinny end.
Fold both loose skinny ends back up to meet the crease. You should now have another accordion. You can now easily refold the map so that the part of it you're using is visible.
Stow your folded map in a gallon-size, zipper-lock plastic bag to keep it clean and dry.
