Planning & Advice

Map Reading 101

Map Reading 101

Now that GPS units are affordable and available everywhere, we really don’t need maps anymore, right? Not exactly. Even the display on your GPS is showing you a map. Learning how to read a map correctly can make travel much easier.

A map is a representation of terrain, showing how things are positioned and how they are separated from one another by distance or direction. It provides a great deal of useful information in a lightweight portable form. There are different kinds of maps for different uses.

For the average driver, a street map is probably most helpful. A street map is what you will see if you look up directions to something on Mapquest, for example. A street map will show major physical features like oceans and rivers, but its focus is on roads. A highway map will show only major roadways over a large area, and a detailed street map will show every known street in a city or district up to the date of the map’s publication.

A topographical map, on the other hand, is intended to detail the physical features of an area. It will show the contours of hills and valleys and the elevations of prominent points. It will track the course of rivers and streams. Topographical maps are intended for those going on foot and are often used in areas where roads are scarce.

There are several key things to look for on a map. First, look at the title of your map. Does it cover the area you want to go to? A map for the eastern United States won’t help much if you’re trying to drive through Arizona.

Every map will have a legend or key, which explains symbols used on the map. On a highway map, for example, a heavy red line may indicate an interstate and two thin parallel red lines may indicate a secondary highway. A yellow-colored area may represent the limits of a city. There are many possibilities, but it’s important to read the legend and understand what it’s telling you. Bodies of water are often represented as blue and parks or forests as green, but check the legend. The particular map you have may have used an alternate coolor scheme.

Orient yourself to direction. The map should have printed on it what is known as a compass rose, the four-pointed symbol that indicates north, south, east, and west. If not, it will at least have an arrow indicating the direction of north. If you stand facing north, east is in the direction of your right shoulder, west is in the direction of your left shoulder, and south is behind you. If you know where you are, and you know what direction you are facing, then you can orient the map the same way and visualize the direction of your destination.

A map will also have a scale, which is determined by the amount of real ground covered by the map. The scale should be displayed somewhere on the map. On a street map, this is expressed as a number of miles per inch. A regional map may show as much as ten miles per inch, where a local street map may show only a tenth of a mile per inch. A common scale for topographical maps is 1:24,000, as used in US Geological Survey (USGS) maps. This means that one inch on the map is equal to 2,000 feet (24,000 inches), a little more than one third of a mile.

A topographical map will also have a contour scale. On the USGS map mentioned above, the contour interval is typically forty feet, meaning that there is an elevation change of forty feet between each two contour lines on the map. The closer the contour lines are together, the steeper the hills are, because the elevation is changing more in a shorter distance. Different scale maps will use different intervals between contour lines. Also, if you are in an area that is very flat, a contour interval of forty feet may not mean much. In these cases, the map may show supplementary contour lines every ten or twenty feet.

Since the earth is round, and maps are printed on a two-dimensional flat surface, there will always be some distortion in the picture the map presents. The larger the area the map covers, the more distortion there is likely to be.

Finding your way with a map can be very simple with a little practice. If you’d like more in depth information, try this website from Princeton University, which offers guidelines for using map and compass to find your way.