Some maps are meant to tell a story, to provide information about the characteristics or history of a place. Others are meant for navigation, to help a user get from one place to another. Trail maps have to do both: show a user how to find and follow a trail, and explain the things of interest he or she will find along the trail. They often look remarkably simple, but have to accomplish a lot.

In addition, trail maps often need to be cheap to print. Imagine the box full of maps at a trailhead. Every passing hiker will grab one. Some hikers will take more than one. Every once in a while, some nitwit will grab all the maps in the box and throw them on the ground or use them to light their campfire. Replenishing the boxfull of maps can get expensive in a hurry.

Trail maps also have to be durable. They will be read in the rain and the snow. Inkjet printing is out of the question, because inkjet inks will run when they get wet. So it has to be laser or offset printed.

As the National Park Service has discovered, a lot of trail users are not sophisticated map readers, so trail maps need to be intuitively clear. A lot of trail users may be visitors from other countries, and may not be able to read the language of the mapmaker well. So text and legends need to play a modest role in trail maps. (As an aside, look at the superb maps produced by the National Park Service in the United States. They are models of intuitive clarity, often needed little or no text or legend, yet are rich in detail.) Tom Patterson, a genius cartographer for NPS, published a thoughtful piece on the design of NPS maps. You can link to it here.

The map below was an exercise in making a trail map to meet all these conditions. It is done in monochrome, so it can be photocopied as needed at very modest cost. A photocopy or monochrome laser print is waterfast, so the map will be readable even if it gets wet. It uses no legend, and just a few small text notes to point out key features of the walk.

This trail is in the borderland between midwestern forest and prairie. That means that the key feature a map follower will use to determine where he or she is on the trail is the landcover. As the hiker steps out of the woods onto open prairie, he can pinpoint his location on the map by finding the place the trail crosses the boundary from forest to prairie. That, however, only raises the question of how to show woodland and prairie. This map uses a variation on a technique called “bump mapping”, basically showing the shadows that would be cast by trees to highlight forest land. It’s completely intuitive: the forest actually looks like forest. And it avoids the need for those annoying legend entries, seen on so many GIS maps, of repeated stylized trees to symbolize forest.

The map also uses an aggressive hillshade (a simulation of the effect of the sun shining on the land) to point out ridges and valleys. The trail follows a distinct ridgeline, so knowing where that ridge is on the map will help the hiker determine his position. Traditionally, this kind of terrain would be shown with contour lines, as appear on USGS topographic maps. Contour lines provide great detail to skilled map readers, but can be confusing to novices. That’s why this map uses the intuitive, but less technical hillshade technique.

Bump mapping can be a technically difficult task (look it up; there are lots of good tutorials out there), in which the mapmaker artificially creates little spots of increased elevation to represent to tops of individual trees. This map uses a simpler method: it just takes a color air photo of the scene and represents one band in grayscale. The result is a map of the shadows actually cast by the tops of the trees.

The map fills one side of a sheet of letter-sized copier paper. The reverse side is reserved for explanations of the individual points of interest.