Topographic Maps aren't cheap. Well, in most cases they aren't free. Protecting your map is protecting an investment that will give years of use. This instructable will demonstrate (and remind myself) how to fold a map to fit in quart sized ziplocks. I prefer the quart size, so I can put the map in a small accessible pocket on my backpack. The trade off is that that puts more creases in the map. Creases serve 2 purposes. They wear out the map in that spot quicker, but more importantly, if your creases are accurate to the edge, they provide north/south and east/west lines.
This instructable is for 1:24k scale 7.5 minute quadrangles in the U.S. For other countries and maps, you may need to experiment a little.
Step 1: Align the First Fold
The first fold is the most important. If the first fold is not aligned, you'll get misaligned north south creases. Lay the map face up and fold along the vertical axis. You should then have half a map and the white side should be visible. Line up the edges well and crease.