It’s a shame how truly underrated the topographic map has become. With the abundance of navigational apps, Google Earth, and smart GPS tools in general, topo maps are a second thought to most, if they’re even thought of at all.
Land navigation is a dying art, mostly because people don’t travel far from their homes, cars, RVs, or places of safety anymore. For the overlanders out there (or the prospective ones), however, a good topographic map is an invaluable tool that the USGS (United States Geological Survey) has been updating since the mid-19th century.
The information density found in topo maps is exceptional. Armed with a compass (preferably with an azimuth) and a topo map, you will find your way out of any situation the natural world has to offer. Once you learn how to read one and break the information down into useful components, exploring the vast unknown will become second nature.
Understanding Topo Maps
A topo map presents a two-dimensional map in a three-dimensional context—those aforementioned context lines. John Wesley Powell, a Union Army Veteran of the Civil War, invented the topographic map mostly because he wanted to map the West for resource acquisition.
The standout feature of a topographic map is the contour lines. These lines delineate elevation, based on the ratio on the map legend. This is a distinctive feature that separates topo maps from others. If that’s all there was to it, it probably wouldn’t be worth writing an article about.
But topo maps include far more, such as bodies of water, mountains, valleys, cliffs, and vegetation. The first thing you’ll notice is that contour lines cover everything, resembling a fingerprint under a magnifying glass. The space between each line measures elevation or drop-off according to the scale on the map.
Like most maps, you’ll find a series of symbols, each one representing a feature. These symbols include campgrounds, national parks, vantage points, shelters, ranger stations, waterfalls, springs, lava, lookout towers, picnic areas, boat ramps, state parks, and more. What’s on the map depends on the purpose of the map.
If you purchase a topo map at a state park, there will likely be a series of symbols representing features specific to that state park. Last but not least, there are three types of contour lines (generally speaking) on a topo map — intermediate, supplemental, and index.
Every fifth line in a series of contours is an index, represented by a bolder, thicker line, and mostly for reference and ease of reading. Intermediate contours add context and detail, while supplemental lines represent features between contours, such as flat areas, crests, banks, levees, etc.
Reading Contour Lines
Most topo maps use a 1:24000 scale, which is to say that every inch on the map is equivalent to 24,000 inches. Now, no one breaks things down into inches over those kinds of distances. So, in general, you’re looking at either a 40′ or an 80′ separation between contour lines.
For instance, if you’re looking at a mountain, start at the contour line at the very bottom. The next contour line, traveling inward toward the peak, represents either 40′ or 80′ of distance vertically. This works the same whether you’re looking at an increase in elevation (mountain or cliff) or a drop-off (river and sea beds).
The distances between contour lines are relevant as well. A tightly packed series of lines indicates a steep climb, while wider spaces indicate a more gentle rise in elevation.
In reverse (valleys and depressions in the ground), the contour lines will feature incremental lines or ticks. This is how you separate valleys from mountains on a two-dimensional piece of paper or in an app. The distances and tightness of the contour lines remain the same.
Of course, mountains rarely just hang out all alone on otherwise flat terrain. If you’re looking forward to a hike in the Smokey Mountains, the chain stretches across many states. On a topographic map, individual mountains within a mountain chain are represented by ‘passes,’ or the area between two or more peaks.
It’s easier to understand from a visual standpoint. Imagine looking down on two styrofoam cups, both resting upside-down on a countertop and pressed up against each other. Even from above, you can see the two circles (the bottom of each cup), and the space between them. A topographic map looks similar, and you can see the space between each mountain, represented as a pass.
Symbols and Legends
No topographic map is complete without a legend. No, that doesn’t mean your purchase of a topo map comes complete with a reincarnated Alexander the Great or Joan of Arc. A legend is simply a block of information, usually found at the bottom of the map, that contains symbols and their definitions.
One topographic map is not the same as the other. Some will have a small, distinctive legend, while others will have so many symbols that it will require a PhD in concentration to memorize them all without falling asleep. For overlanding navigation, there are only a handful that you really need to know.
This includes various land features, land survey outlines (to keep you from trespassing onto properties), campgrounds, hospitals, fire stations, bodies of water, and roads. USGS provides a breakdown of most of the symbols you should at least familiarize yourself with, but far from all of them.
Using Scales and Coordinates
One of the best scales you can use is your own feet. Take a single, normal step forward and measure the distance from the back of your heel (starting point) to the front of your toe (ending point). Now, it’s not perfect, but it will allow you to calculate the distance traveled by multiplying the steps you’ve taken by the distance you measure.
Next, look at the scale on your topographic map. In the above instance, we referenced a 1:24000 scale, with every inch on the map representing 24,000 inches or .37 miles. There are 5,280′ in a mile or 1,760 yards. So, 24,000 inches equals 2,000′, which equals .37 miles. Breaking these numbers down helps you understand two things: how far you’ve traveled, based on the step-measuring exercise, and how far you have to go.
Magnetic Declination
The next thing you need to understand is magnetic declination. This is the angle between magnetic north and true north, with the former being fairly malleable at times. To find the magnetic declination and keep yourself oriented north, you’ll need your topographic map and a compass with an adjustable declination.
The topographic map you are using should have the declination angle on it, which is very useful. However, since magnetic north changes, a topographic map that is four years old is useless for this exercise. You need to have a recent map or you need to look up the declination value for your area.
- Lay your map out flat, oriented with the north at the top
- Choose or mark a point on the map
- Place your compass over the point
- Adjust your bezel to account for the declination of your area
- Rotate the compass to place the magnetic arrow in the orientation arrow
Now, it can get more complicated than that, especially if you calculate the grid north with true north and magnetic north. But, for most “vanlife map skills” necessities, this will do the trick and get you where you are going.
Latitude and Longitude
On most topographic maps, latitude is represented on the left or right side of the map, while longitude is on the top or bottom, east to west. Most of these maps don’t include overlapping lines because they will make the map more convoluted and difficult to read. However, you can use a ruler to draw out your latitude and longitude based on your current position.
Knowing your lat and long location is critical if you are using a GPS device, such as a Garmin eTrex or Rino (either of which are highly recommended for hiking). Not only will these devices help you navigate, but they will also send your coordinates to your contacts periodically, or in case of an emergency.
Topographic Map Practical Tips for Overlanders and Vanlifers
First and foremost, a good topographical map looks way more complicated than it really is. The most important thing to understand is the simplicity of it and how you can use the contours on these maps to visualize your terrain and what’s ahead of you.
Some things you learn, especially as you get deeper into overlanding, are more about you than the map you carry. A topo map is a tool, and the skills you bring to the table make it more so. For instance, when you enter the woods, check the sun’s location. This will help you orient yourself when you emerge later, regardless of the time of day.
Know your stride length. While it’s not a perfect measurement, it’s a solid indicator of distance traveled when you have no other means to gauge it. Get a good compass, not a cheap one. It needs to have an adjustable bezel, an orientation arrow, and an azimuth. Once you determine your exact direction via magnetic declination, you can use the azimuth to pick out an object in the distance.
With north aligned with the orientation arrow, picking out a distant location based on line of sight and the orientation arrow will keep you in a straight line over very long distances. Study your contour lines and practice visualizing them in three dimensions. Pick out flat areas and mark them down for hiking breaks.
Keep your maps dry and safe. Never depend on your electronic devices. The map will last, but the batteries will not.
Common Mistakes and How to Avoid Them
The most common mistake hikers and overlanders, in general, make is not letting someone know where they are going. Not only should someone know, but they should also know what time you will arrive at your destination and what time you plan on contacting them. If you think this is silly, watch the movie 127 Hours, which is based on a true story.
Don’t depend on singular navigational tools. For example, you should carry more than one map, avoid depending wholly on electronic GPS devices, avoid depending on your smartphone, and constantly think outside the box. There are more than a few navigational tools out there, and you should spend more time learning the old-school methods than embracing the new ones.
Remember, Viking explorers navigated the seas without an iPhone 15 Pro Max. You should partner up whenever possible. We’re not saying never venture out alone, but it’s always a safer bet to have someone beside you that will have your back in case of an emergency.
Another mistake newbie adventurers tend to make is not understanding the tools they carry with them. The good thing about a compass, map, protractor, GPS device, sundial, azimuth, and more, is that you can practice with all of the above in your backyard. Know your stuff like you know your own thoughts — it could mean the difference between life and death.
Nature doesn’t care if you don’t know how to use your compass, and it won’t forgive you for neglecting to learn topo map reading. This map reading guide exists, so you won’t make that mistake. It’s exciting to get out there and see the natural world and the wonders it has to offer. Just make sure you do it on your terms, with the knowledge and toolset necessary for the effort.
Hone Your Skills With the Following Courses
The best way to truly get started with land navigation is to take a course. Below you will find a couple of options anyone can choose to get started.
- Description: REI offers various navigation classes, including map and compass navigation and GPS navigation. These courses are hands-on and often held in outdoor settings.
- Website: REI Outdoor School
- Description: Gaia GPS offers online courses in backcountry navigation, including using maps, compasses, and GPS devices.
- Website: Gaia GPS Navigation
Each of these courses offers a blend of theoretical knowledge and practical skills, ensuring you’re well-prepared for any overlanding adventure.
Conclusion
A topographic map is a wonderful little tool of old-school usefulness. Alone, it’s often enough to outshine your latest devices in what it is designed for. There’s nothing quite as exciting as learning the ins and outs of land navigation, mostly because it teaches you as much about yourself as it does navigation.
Understanding a topo map is not hard, but it’s not as simple as a quick glance and a YouTube video either. Take your time. Learn the ins and outs of the contour lines, and what they mean on your particular map. Make sure you’re geared up and that you understand how to integrate your compass with line of sight, your topo map, distance, and direction.
Most of all, have fun learning a fundamental survival skill that few people know and understand anymore. When a plane can drop you off in an unknown location, somewhere on the planet, and you can find your way out, you’re good to go.
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