Topographic Map Skills Primer

The level of detail provided by topographic maps make them extremely useful for hiking and exploring the outdoors. Knowing how to read a topographic map is an indispensable survival skill.

We’ll cover the basics here and provide some online sources for finding topographic hiking maps.  We will also feature some external sites that teach map skills & orienteering in greater detail.

What is a Topographic Map

Topographic maps render the three-dimensional ups and downs of the terrain on a two-dimensional surface. The topographic map shows a cross sectional view of the terrain, known as a topographic profile.  If you sliced through and pulled away a portion of the earth, and viewed it from the side, the surface would be a topographic profile.

Topographic maps describe the shape of the land and portray both natural and significant manmade features, such as mountains, valleys, waterways, dams, roads, boundaries, and bridges. For this reason, the topographic map remains an indispensable tool for measuring and navigating terrain.

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Elements of a Topographic Map

Contour Lines

The shape and elevation, or contours of the land are represented by brown contour lines. The contour lines connect points of equal elevation, so elevation remains constant if you physically follow a contour line. And, if you cross these contour lines, you will be either climbing or descending.

• Contour lines are printed in light brown.  They do not contain the elevations.
• Every 5^th line is an index contour.  These lines are printed in darker brown.  They contain the elevation.

Contour Intervals

The equal spacing between the contour lines is the contour interval. Depending on the terrain, this interval may depict a small

vertical rise or a large vertical rise. For instance, in a mountainous area, a 100-foot contour interval will indicate a 100 foot elevation rise for each line. The contour interval is defined in the margin area of the map.

To determine elevation, pay attention to the amount of space in between the contour lines.

• Lines close together indicate a steep grade.  Expect to climb or drop!
• Lines widely spaced apart (or not shown at all) indicate a flatter terrain.

Symbols & Colors

Features of the land, either man-made or natural, are represented by colored symbols. These signs are usually explained in the margin of the map. The standard colors for most topographic maps represent the following features:

Black: man-made features such as trails, railroads, wilderness boundaries, roads

Blue: Water ways such as a river, lake, stream, or swamp

Green: Vegetation or cleared vegetation, such as forests, vineyards, and orchards

Brown: Contour lines, contour elevations

Red: Main roads, urban development and special features

See a complete list of topographic symbols

Scale

Scale refers to the relationship between distance on a map and the corresponding distance on the ground. The scale represents this ratio in a fraction format. For instance, a 1:24,000 scale means 1 unit of measure on the map is equal to 24,000 of the same units of measure on the ground. Therefore, a 1:24,000 scale means that one inch on the map is equal to 24,000 inches (2,000 feet or 609.6 meters).

• The map scale is defined on the top / bottom margin of the map

There are many different map scales produced. The most widely distributed topographic maps in the U.S. are produced by the United States Geological Survey (USGS). These are the 7.5-minute 1:24,000 scale, where 1 inch represents 2,000 feet. A scale of 1:25,000 is commonly used for countries based on metric units, where 1 centimeter = 0.25 kilometers. Other common scales include the 1:100,000 and the 1:250,000 scale.

• Why is 1:24,000 scale referred as 7.5 minutes?  These maps cover a 4-sided area which is divided into quadrangles bounded by 2 lines of longitude high and 2 lines of latitude wide. A 7.5 minute map shows an area that spans 7.5 minutes of latitude and 7.5 minutes of longitude, where 60 minutes equals one degree of angle.

How to choose the right scale

Medium-scale maps (e.g. 1:24,000) cover smaller areas in greater detail, whereas smaller-scale maps (e.g. 1:250,000) cover larger areas in less detail. The most important consideration in choosing a map is picking the correct scale. Ensure the scale will provide the level of detail required for its intended use. A few examples:

• 1:250,000 scale: 1 inch ~ 4 miles (less detailed; adequate for driving to the trail head)
• 1:100,000 scale: 1 inch ~ 1.6 miles (more detailed; adequate for planning a hike)
• 1:24,000 scale: 1 inch ~ 2,000 feet (detailed; adequate for hiking the trail)

Sources for hiking maps

Most of these maps are printed on durable polyart material, which is tear-resistant and waterproof.

• USFS – hiking trails produced by the US Forest Service (USFS). We have been extremely impressed with the accuracy of these maps when hiking throughout the forests in the state of North Carolina.  Find USFS maps.
• Trails Illustrated – hiking trails produced by National Geographic Maps covers many of the US national parks and forest areas. We find the forest maps produced by the US Forest Service (USFS) to be more accurate for hiking in the US national forest. In cases where USFS maps do not exist or are extremely outdated, Trails Illustrated is a suitable alternative. Find Trails Illustrated maps.
• Earthwalk Press – hiking trails produced by rangers from the National Park system. The maps contain useful information about hiking trails and camping areas in the US National Parks. These maps often cover areas for which no other hiking map exists.  They cover a the Wind River Range, Grand Canyon, Mount Rainier, Grand Teton, Yellowstone, and Northern California.
• Tom Harrison Maps – topographic maps for hiking areas in the state of California.  Find Tom Harrison Maps.

Sources for planning / driving to hikes

• US Geological Survey 1:24,000 – offers a few topographic maps for hiking which provide excellent detail, but often only cover small areas of the forest. The less detailed USGS maps are better for planning hikes. Many maps shift North around so the map fits on the page, which can cause confusion while hiking. USGS topographic maps do not shift North. North is always at the top of the map.  Most hiking trails can be found here and you can print out these maps free.  Find USGS maps.
• DeLorme Road Atlas & Gazetteers by State – These topographic atlases offer excellent accuracy for driving to trail heads, and we have discovered numerous scenic routes and old logging roads from studying these maps.  They also offer other useful information by state for recreational areas, trails, attractions, car camping, historic sites, fishing sites, boat launches, scenic drives, etc.
• Topo! Software from National Geographic for printing your own maps at home.  We have never tried the software, but it sounds nice.

Sources for learning more about how to read topographic maps