by Keith Hamburger

Created on: May 22, 2008   Last Updated: May 30, 2008

A map is a representation of what exists on the ground in the area covered by that map. By looking at a map you can determine what you can expect to find at a given location, determine where you are and get guidance on how to get from where you are to where you want to be.

Most of us have used a highway map to determine how to get from point A to point B. A highway map will show roads, cities and other features of interest to people traveling on roads but don't show much detail of use to people traveling away from developed areas.

For planning backcountry travel we use a topographic map. In addition to providing representation of altitude through contour lines, topographic maps give more information to the local area because they are produced at a larger scale. Large-scale maps cover a narrower portion of the Earth's surface in greater detail than small-scale maps.

Scale is represented as a ratio of 1 to another number. The most common maps used in the United States use the English system of measurement; inches, feet, yards and miles. In the English system the 1 represents one inch on the map and the following number represents the number of inches on the ground. Most US Geological Survey (USGS) topographical maps in the Continental US have a ration of 1:24000. This means that if you measure one inch on the map that will represent 24,000 inches on the ground, or 2,000 feet.

Such a map is considered a large-scale map. Since a ratio is also considered a fraction, 1:2, or one half, is larger than 1:4, or one quarter. In the same way a scale of 1:24,000 is larger than a scale of 1:50,000. A large-scale map covers a smaller area than a small-scale map

Smaller scale maps are also produced by the USGS. Scales of 1:50,000, 1:100,000 and greater, including multi-state maps at 1:2,000,000. These maps cover a much larger area in less detail. A small-scale map may be useful for determining areas you might wish to visit and can help you get there. But, since such a map will lack the detail of the smaller scale map it won't help as much in getting around when your ready to put boots to dirt.

When planning the details of your backcountry travel it is important to know exactly what you will be facing. For this purpose a large-scale map should be used. Once you've decided the area you wish to visit you should obtain maps of the area in large scale. The USGS 1:24,000 scale maps are ideal for this purpose.

On such a map even the smallest detail is included. Footbridges, ruins and many

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