In This Chapter
Stretching the truth
Understanding how maps are dishonest
Weighing the pluses and minuses of globes and flat maps
Analyzing different maps
Looking out for really bad maps
I magine a million-dollar map contest. The only thing you have to do to win is to supply an exact map of the entire Earth that’s flat. Here’s how to enter!
1. Get your hands on a globe.
2. Peel off the map of the world in such a way that you end up with one big piece of map peel. (You may want to use somebody else’s globe because this procedure results in the globe’s complete ruin.)
3. Lay the map peel on a flat surface so that the two surfaces are completely in contact but without distorting the original map in any way. You can cut the map if you want, but pulling and stretching it is prohibited.
You are absolutely right if you think it’s going to be tough to submit a winning entry. Actually, it’s impossible. You can’t take a spherical surface, such as Earth, and lay it down flat without distorting the original image. This fact, however, hasn’t deterred people from making flat maps of the world or parts thereof. And, to do that, the mapmaker has to figuratively pull it here and stretch it there. The result is a map that’s full of distortion. Full of distortion? Well, simply put: Maps that lie flat lie!
Maps of the world are among the most basic aids to geographic learning. Many people take it for granted that they are truthful. But in reality, all flat maps of the world lie — they simply cannot help it. As a novice geographer, it is important that you appreciate that simple fact and understand the ways in which maps distort their portraits of your Earthly home. This chapter shows just how flat maps lie.
Seeing the Light: Map Projections
Accordingly, this chapter is about mapmaking with emphasis on the distortions that are inherent in flat maps of the world. But first, some basic vocabulary is in order. A map is a representation of all or part of Earth’s surface. Cartography is the field of mapmaking, and a cartographer is a person who makes maps. Way back when, cartography was pure freehand, and I do mean way back. The oldest known map is a 5,000-year-old clay tablet that shows physical features of Mesopotamia. Later, cartography became associated with instruments and techniques that most people think of as drafting. Nowadays, most cartography is done with the aid of a computer.
Flat maps are called projections because, theoretically, making a map of the world or a large part of it involves projecting a globe onto a piece of paper or similar flat surface. Imagine, as shown in Figure 4-1, a clear plastic globe with a light source at its center. When the bulb is turned on, light passes through the glass sphere and projects the lines from the globe’s surface onto a receiving flat surface. The result is a flat map of Earth — a projection. (Not to be a wise guy, but I really do hope you’ve seen the light because, theoretically at least, that is what projections are all about.)
Projection has two meanings. On the one hand, it refers to the process of transferring a globe to a flat surface. On the other hand, projection refers to the map itself, the result of the transferal. One could say, then, that projection (transferal) results in a projection (flat map).
The diagram that shows the globe and light bulb is a simple model that most people find helpful in visualizing how projections are made. In reality, projections aren’t made with a glowing light bulb in the center of a globe. Instead, projections are products of mathematical formulas, trigonometric tables, and things of that ilk. The specifics are pretty tedious; fortunately, trying to explain it all in language that even I can understand is beyond the scope of this book. As a novice, it will be sufficient for you to appreciate that different projections exist, but none are totally truthful.
Earth’s shape: Sphere-like, not spherical
People often say that Earth is a sphere. Not so. By definition, a sphere is a curved solid whose surface is always the same distance from its center, no matter at what point of the surface. Technically, Earth doesn’t fit that definition. Instead, Earth is an oblate spheroid, meaning it is somewhat flattened at its poles, or, if you prefer, it bulges somewhat around the Equator. The average distance from Earth’s center to the Equator is about 26 miles farther than the average distance from Earth’s center to the poles. Compared to the size of Earth, 26 miles isn’t a great distance, but it’s enough to make Earth not a real sphere. It’s better to say Earth is sphere-like, or an oblate spheroid.
Earth’s rotation causes its oblate-ness. The speed of Earth’s rotation is much faster at the Equator than near the Poles. This difference in speed may not be obvious, so think of it this way. Earth’s circumference measured along the Equator is about 25,000 miles. If you stand at a spot on the Equator for one day — for one full rotation — you’ll travel 25,000 miles. In contrast, if you stand a foot or two from the North Pole for one rotation, you’ll only travel a few yards. Obviously, somebody who travels 25,000 miles in one day is moving much faster than somebody who travels a few yards in the same time. So, the area near the Equator is spinning much faster than other parts of Earth. The outward, or centrifugal, force the high speed of rotation causes is so great that Earth bulges around the Equator as a result.
Realizing Exactly How Flat Maps Lie
The business of making map projections requires a somewhat deviant personality. Cartographers know that maps that lie flat lie. They know for certain before they begin a project that it’s absolutely impossible to create a flat map that looks exactly like the world. Does that deter them? Nope. No way.
Cartographers have developed literally dozens of different kinds of map projections over the years. Each one contains some degree of misinformation. If you’re like most people you’ve given little or no thought to map projections nor have you suffered from not doing so. Or have you?
Understanding the facts about maps can’t help but make you a better-informed person. Maps are a common means of communicating information. They pop up in newspaper articles, magazines, books, TV programs, and elsewhere. Because mainstream media is in the business of providing factual information, people may understandably assume that the maps they’re looking at are accurate. But maps that lie flat lie, and there’s nothing anybody can do about it — except maybe understand the nature of the distortions and appreciate that flat maps should be interpreted with a certain amount of caution.
There’s an old saying in cartography: Close counts in horseshoes, nuclear war, and map projections. (Actually, I just now made that up; but because this chapter is all about lying, what the heck!) Cartographers know projections lie, so their objective is to get as close to reality as possible. But enough of this blabber about maps that lie, it’s time to consider a practical example that involves some honest-to-goodness maps. Or rather, some not-so-honest-to-goodness maps.
Singapore, please. And step on it!
Suppose you live in New York City and are preparing for a trip to Singapore, almost halfway around the world. In planning your trip, you decide to minimize your flying time and also to stop somewhere for a day or two, just to break up your travels. A friend suggests a stopover in Rome, Italy. But another friend tells you to layover in Helsinki, Finland. You have no idea which choice is best, so you decide to find out by plotting the two cities on a map (see Figure 4-2).
Accepting the principle that a straight line is the shortest distance between two points, the map seems to make your choice pretty clear, doesn’t it? The itinerary to Singapore via Rome is apparently much shorter than the route via Helsinki. As a result, you call your travel agent and make the appropriate bookings.
Upon hearing your travel plans, your second friend is shocked. “You’re not going by way of Helsinki?” To show your friend the wisdom behind your choice, you take out your map and note the obvious: The linear distance from New York to Singapore is shorter via Rome. Whereupon your friend produces a map of her own (see Figure 4-3).
Looking at the map in Figure 4-3, three things are suddenly obvious.
First, the global view in this map is much different than in Figure 4-2.
Second, the results are different, too. In Figure 4-3, going to Singapore via Helsinki appears much shorter than the route via Rome.
Third, one of these maps is lying, but which one?
If you have a globe handy, you can determine the shorter of the two itineraries from New York City to Singapore. Get a string, pull it taut, and place it on the map so that the string connects New York City and Singapore. What you observe is that the string passes over the Arctic Circle and shows that a stopover in Helsinki is a minor detour, but a stopover in Rome is a major detour. If you don’t have a globe, you can’t do this demonstration, can you?
Applied Geography: Putting your best projection forward
Figures 4-2 and 4-3 provide different perspectives on air routes between New York City and Singapore. While this may seem a strictly academic exercise, airlines that compete on long-range international itineraries take the matter very seriously. There’s an old saying: “Time is money.” And for that reason many business travelers (if they have a choice) prefer the shortest route to get them where they’re going. Airline executives know this. Accordingly, marketing strategies sometimes involve making maps that present the airline’s route system in the best light possible. And doing that, of course, involves choosing the best possible projection.
Wading through lies in search of the truth
The maps in both Figure 4-2 and 4-3 are lying. But the map in Figure 4-3 provides the most accurate — that is, most globe-like — perspective regarding the shortest route between New York and Singapore. I’d really love to be able to prove that to you right here on the page of this book, but therein lies the problem — literally. This page is flat. To find out which route is shortest, you need a map that really looks like the world itself. That is, you need a globe.
Because a globe doesn’t come with this book, you have to come to grips with the four ways in which maps can lie: distance, direction, shape, and area.
Most flat maps lie with respect to at least two characteristics, and some lie in all four aspects. In modest detail, here is the lowdown on exactly how and why these fibs occur.
Theoretically, transferring a curved Earth to a flat map involves selectively stretching some parts of Earth’s surface more than others. For example, imagine two cities are 1,000 miles apart and the land between them gets stretched a great deal during the map-making process. Now imagine that elsewhere on Earth, two other cities are also 1,000 miles apart, but the land between them gets stretched just a little to make the very same map. On the resulting maps, the distance of 1,000 miles isn’t portrayed the same.
The situation with direction is pretty much the same as with distance. By stretching a globe to make a flat map, true directions become incorrect. If some parts of the globe are stretched more than others, then a north arrow placed on one part of the map may point in a different direction than a north arrow placed elsewhere.
Actually, it’s possible to make a map that keeps true directions throughout its surface. The Mercator Projection, a rather famous map introduced later in the chapter, is an example. But maintaining true direction can only be achieved by distorting something else. As the Mercator Projection shows, that something else is distance and area.
Shape refers to the outline of objects on Earth’s surface. In the process of projection, you can transfer a continent or island from a globe to a flat surface while keeping its shape pretty shape intact. Then again, you can make a complete mess of things because stretching here and pulling there is part and parcel to the projection process and may play havoc with shape.
For example, compare Greenland in Figures 4-2 and 4-3. Notice that the island appears very differently in the two maps. Greenland’s shape is virtually correct in Figure 4-3 because the lines of longitude meet at the North Pole, just as in reality. In Figure 4-2, however, Greenland is seriously misshapen because the lines of longitude do not meet at the North Pole but are instead spread apart in the polar area. The result is a greatly distorted Greenland.
But before we sing the praises of Figure 4-3, compare the shape of Northern Africa on both maps. Africa appears much more accurately in Figure 4-2 because in that map, the spacing of North Africa’s lines of latitude and longitude are pretty much true to life. In Figure 4-3, however, North Africa appears to have become an accordion. It has been stretched laterally out of proportion to its true shape. That happens because as the lines of longitude extend outward from the center point — the North Pole — the projection excessively stretches the distance between them. As a result, North Africa has a flattened appearance.
Area refers to the size of objects on Earth’s surface. As is the case with shape, you can transfer (project) some features from a globe onto a flat surface while keeping sizes accurate relative to other objects on Earth’s surface. Then again, you can make a complete mess of things. As to the reasons why, well, I apologize that this is sounding like a stuck record, but the simple fact is that stretching here and pulling there to make a flat map screws up the relative sizes of continents, oceans, and everything else on Earth.
Isn’t there a truthful map anywhere?
Many maps are honest. But before I point some of them out to you, let me re-emphasize that flat map untruthfulness is related to Earth’s curvature. Obviously, big portions of Earth involve more curvature than small portions.
A flat map of the entire world is going to lie a lot because so much curvature is involved. In contrast, a flat map of the United States has the potential of being more truthful (strictly geographically speaking) because the area of the United States has less curvature than the entire world. A flat map of the town or area in which you live — well, now we’re talking little fibs as opposed to big lies because your local surroundings do not have that much of Earth’s curved surface. And if we’re talking about a map of your back yard, that could be an absolutely honest map because Earth’s curvature over such a small space is virtually nil.
So, yes there are honest maps, but only ones that involve relatively small portions of Earth’s surface. Geography, however, involves study of the whole Earth or portions of it that typically are bigger than your backyard. That means curvature is involved and therefore the likelihood of dealing with dishonest maps.
One and only honest map: The globe!
A globe is a spherical map of the world. I’m almost embarrassed to write that because everybody knows a globe when they see one. But over the years, I’ve been amazed at the number of people who tell me that a globe isn’t a map because, according to them, maps are by definition flat. Not so. A globe is a representation of Earth; so, by definition, it most definitely is a map.
The globe is the one and only honest map of the world. Because the globe has the same shape as Earth, the appearance of Earth on a globe is free of distortion. Put differently, a globe doesn’t lie flat so it doesn’t lie at all. On a side note, globes are very attractive and fun to look at. Place one conspicuously in your home and guests are likely to think you have good taste and are very intellectual.
Honesty is the best policy, except . . .
Globes are truthful and the truth counts, but globes have four major disadvantages relative to flat maps.
Limited field of view
No matter how you look at a globe, you can never see the whole world at once (unless you’re in a room full of mirrors, but forget that as a practical solution). Indeed, when you calculate the geometry, you cannot see even half of the world at once on a globe. However, it’s often desirable to view Earth in its entirety or to visually compare far away parts of the world. These perspectives aren’t possible on a globe but are possible on flat maps.
Globes are comparatively more expensive than maps. I checked the Web site of a well-known company that makes wall maps, atlases, and globes. The basic globe (12-inch diameter) sells for about six times the price of the basic wall map and about twice as much as a really good atlas. Want a map of the world without paying an arm and a leg? Buy a flat map.
Lack of detail
Because globes entail the whole world they tend to show less detail. Next time you’re face-to-face with the typical desktop globe, look for the region in which you live. Unless you are a resident of a big city, there’s a good chance the globe doesn’t show your hometown. And suppose you wanted a detailed map of your home area. How big would a globe have to be to include that kind of information? Probably as big as the Empire State Building. Globes are good for giving you the big picture, but if you want to view an area in detail then you better get a flat map.
Inefficient data storage
Two paragraphs ago, I mentioned a globe with a 12-inch diameter. If you want to take it somewhere, you can’t fold it up and put it in your pocket. It probably won’t even fit in your backpack. In contrast, I have an atlas that is 12 inches long, 8 inches wide, 1.5 inches thick and contains more than 100 maps. Better still, I have a pair of CD-ROMs that contain a virtual map encyclopedia. By comparison, globes are very inefficient when it comes to data storage. (Besides, it’s very difficult to walk around carrying a globe and look cool at the same time.)
How serious are these disadvantages? So serious that you’ll need to amend a pearl of wisdom you learned as a kid. Honesty is the best policy except when it comes to globes. Globes are truthful, but the truth in this case comes at a very high and bulky price.
Telling the truth, but telling it slanted
It’s certainly true that geography seeks to provide accurate information about Earth. It’s also true that flat maps are inaccurate and therefore counterproductive to the pursuit of truth — at least in a limited sense. But the four disadvantages of globes are so serious that geographers prefer dispensing with honesty (globes) and using flat maps even though they lie. Indeed, those disadvantages of globes may be recast as advantages of flat maps:
Unlimited field of view: You can show as much or as little of Earth as you want on a flat map.
Low cost: Flat maps cost much less than globes. In fact, a good-sized atlas containing hundreds of maps may cost less than a single globe.
Accommodates detail: Want to show a small area in great detail? Not a problem on a flat map.
Efficient data storage: You can fold up a flat map and put it in your pocket. Or you can put the equivalent of a hundred globes in a single atlas and carry it in your hand or stick it in your backpack. Ever try carrying 100 globes?
The bottom line is that it’s okay if flat maps lie, as long as you know you are being lied to and understand the nature of the lie.
Different Strokes for Different Folks: A World of Projections
If you are a veteran map-gawker, you know that all world maps don’t look the same. And if you’re not, then look again at Figures 4-2 and 4-3. Figure 4-2 looks something like a rectangle, shows the entire Earth, and is centered on the intersection of the Equator and Prime Meridian. Figure 4-3 is a circle, shows only the Northern Hemisphere, and is centered on the North Pole. As mentioned earlier, the two maps offer contrasts with respect to the ways maps lie: distance, direction, shape, and size.
The appearances in the maps differ because of different kinds of projections. That is, the maps are products of different methods of transferring the curved globe to a flat surface. Over the years, cartographers have developed literally dozens of different projections. Most maps are accurate and/or visually pleasing in some respects, although inaccurate or visually displeasing in other respects.
At this point, you may feel like saying, “Look, Charlie, why don’t you spare me the details? Just tell me which projection is the best one so we can move on to the next chapter.” I wish it were that simple; I really do. But the simple fact is that a winning projection doesn’t exist. Every projection has good points and bad points. The trick is to know the pluses and minuses of particular projections so that choosing the best map for specific purposes is easier. It really is a case of different strokes for different folks, or at least different projections for specific situations.
If you’re starting to think that this is a somewhat arcane field of study, well, you’re right. As a novice geographer, you don’t need to commit map projections to memory. (I know several professors of geography who don’t go near this stuff!) What is important, however, is that you appreciate the variety and complexity of map projections and understand that even though all flat maps lie, some do a pretty good job of showing all or part of Earth.
All in the (map) family
Generally speaking, map projections belong to one of three families: azimuthal, cylindrical, and conic (see Figure 4-4).
Azimuthal (or planar): A flat piece of paper (or plane, hence planar) is placed against the globe. The globe is then projected onto the flat paper, rendering a flat map.
Cylindrical: A paper cylinder is placed over a globe. The globe is projected onto the paper. The cylinder is then cut vertically and unwrapped from the globe, yielding a flat map of the world.
Conical: A conical paper hat is placed on the globe. The portion of the globe under the hat is projected onto the paper. The paper is cut in a straight line from its edge to the tip of the cone. The cone is then opened up and put down flat.
This reminds me to remind you that the process of projection does not literally involve projecting a globe onto a flat surface. Instead, mathematical formulas are used to plot the locations of lines (latitude, longitude, continental boundaries, and so on) on maps. Thanks to satellite imagery and high-altitude photography, you can now check the accuracy of your work in a way that was never possible before.
Five noteworthy liars
Here are five rather well known projections that represent the range of formats shown in Figure 4-4. There will not be a test over this. I repeat, there will not be a test. So don’t try to memorize this stuff, but instead, just sort of let the maps visually soak in to give you an appreciation of the variety of projections that are available.
The Mercator projection
Gerhard Kremer, who’s much better known by his adopted Latin name, Gerardus Mercator, developed the Mercator projection in 1569. This cylindrical projection (see Figure 4-5) is easily the most famous world map of all time. Mercator crafted his projection to aid navigation, and in that regard, the map is a gem. Straight lines on this map correspond to true compass bearings so a navigator could use it to plot an accurate course. This achievement was a very big deal in the late 16th century, and by the middle of the 17th century, a majority of Western European navigators swore by this map.
Because of its seafaring fame, the Mercator Projection later came into widespread use as a general-purpose map. That is, it found its way into classrooms as wall maps and into books and atlases. It became more or less the official world map, which is unfortunate because, although the shapes of landmasses are fairly accurate, the projection is extremely distorted with respect to size.
Notice that the lines of longitude on the Mercator projection don’t meet at the Poles, as is the case in reality. Instead, the map shows the lines of longitude as parallel lines. This means that the North and South Polar regions have been stretched and become lines (the top and bottom borders of the map) that are as long as the Equator — 25,000 miles. One result is that land areas become disproportionately enlarged the closer they are to the areas of maximum distortion — the Poles. Alaska and Greenland are good examples. Alaska appears much larger than Mexico, while Greenland appears much larger than the Arabian Peninsula. In reality, Mexico is larger than Alaska, and the Arabian Peninsula is bigger than Greenland, but you’d never know by looking at the Mercator projection.
Because of distortions like these, the Mercator projection has fallen out of favor as a general-purpose map. No single map has replaced it. Instead, makers of wall maps and atlases have been using a number of other projections (some of which are mentioned below) that give a truer view of the relative sizes of Earth’s feature.
The Goode’s Interrupted Homolosine projection
Noted American cartographer Dr. J. Paul Goode (1862-1932) developed this cylindrical projection (see Figure 4-6). It’s an equal area projection, which means that the land areas are shown in their true sizes relative to each other. In that respect, Goode’s projection is far superior to Mercator’s. Interrupted refers to the map’s outline. Earth is cut into once above the Equator and three times below it. Therefore, the Northern Hemisphere appears as two lobes and the Southern Hemisphere as four lobes.
As a result, the map’s outline is not a rectangle or some other compact form, but instead is interrupted. The word homolosine reflects the fact that Goode’s map is a combination of two other projections: the Mollweide homolographic and the Sinusoidal. (Whether or not you ever learn what that means, I will be happy to give you extra-credit for correct spellings.) Although Goode’s projection appears in various atlases and despite its desirable equal-area attribute, many people are visually uncomfortable with its interrupted format.
Why is an atlas called an atlas?
An atlas is a book of maps. For the longest time, maps were published singly and tended to be stored as rolled-up scrolls standing in a corner or stuck into honeycombed shelves. Gerardus Mercator was apparently the first person to compile a book of maps. Whatever the reason, his publisher decided to decorate the cover with a likeness of Atlas, the legendary Greek giant who supported the heavens on his shoulders. But in this rendering, a big globe replaced the heavens giving us the familiar image of a bent-over Atlas bearing his Earthly burden. Other books of maps copied Mercator’s idea and the image of Atlas on the cover or title page became standard — which is why such volumes are called atlases. But this short history leads to speculation about what we would now call a book of maps had Mercator’s publisher decided to put something else on the cover. Who knows? Maybe I’d be advising you to go out and buy a really nice aardvark.
The Robinson projection
Dr. Arthur H. Robinson, a noted American cartographer, introduced this cylindrical projection in 1963 (see Figure 4-2). If you lie really well, people may not notice. In fact, they may love you because of it. With all due respect and admiration to the good doctor, his map lies really well!
Although the projection contains distortion with respect to size and shape of land areas as well as to distance and direction, it has good overall balance with respect to these elements. In particular, the high latitude land areas are much less distorted than in the Mercator projection. Furthermore, Robinson’s format does not have the interruptions of Goode’s map. As a result of these pluses, in 1988 the National Geographic Society adopted the Robinson projection for its world maps. Partly because of the prestige and publicity of that designation, the Robinson projection has become one of the popular choices among publishers of atlases and classroom wall maps.
The Lambert Conformal Conic projection
Johann Heinrich Lambert (1728-1777), a noted German physicist and mathematician, developed the Lambert Conformal Conic projection in 1772 (see Figure 4-7). Projections cannot correctly show the shapes of large areas, but they can be drafted such that the shapes of small areas closely conform to reality. That is what the Lambert Conformal Conic Projection achieves.
Accuracy of shape (conformality) is most closely achieved where the cone, which is intrinsic to a conic projection, touches the globe. If you refer back to Figure 4-4, you can see that the conic projection makes contact in the latitudinal vicinity of the United States. For Americans, therefore, this projection is noteworthy because it is commonly used to make maps of their country.
The Lambert Azimuthal Equal Area projection
The same Herr Lambert who developed the conformal conic projection (see the preceding section) presented the Lambert Azimuthal Equal Area projection in 1772 (see Figure 4-3). Because it’s an azimuthal projection, as shown in Figure 4-4, it portrays only a hemisphere, as opposed to the entire world. On the other hand, it has two positive aspects: Areas are shown in true proportion to the same areas on Earth and, as revealed in my New York-to-Singapore exercise (see “Singapore, please. And step on it” earlier in this chapter), long-range directions are depicted with a fair amount of accuracy.
Mapping a Cartographic Controversy!
If you’re under the impression that the world of map-making is rather staid and geeky, you’re right. In recent years, however, a map known as the Peter’s projection has come along and stirred things up. Although this projection is controversial, it serves as an excellent example of why average citizens and novice geographers ought to know the facts about flat maps.
The Peter’s projection was introduced and subsequently promoted in 1972 by Arno Peters, a German historian (see Figure 4-8). It’s also the subject of his book The New Cartography (Die Neue Kartographie). As far as accurately showing the world is concerned, this map lies with the worst of them. The appearance of the continents has been likened to wet laundry hanging out to dry. Given its distortion of the shape of land and water bodies, geographers tend not to take this map very seriously. But this projection has been adopted — even championed — by a number of influential agencies that, like Herr Peters, are actively promoting its use.
Advocates of the Peter’s projection say it renders an important measure of cartographic justice for tropical Third World regions. They claim that by inflating the size of high-latitude regions relative to the tropics, the Mercator and some other projections present a Europe-centered view of the world that denigrates Third World countries in Asia, Africa, and South America. Proponents point out that the Peters projection is an equal area projection that shows tropical regions in their true size relative to, say, Europe and North America. As a result of such advocacy, several agencies with strong interests in the Third World (including the National Council of Churches, UNICEF, and UNESCO) have adopted the Peters projection as their official depiction of the world.
When you look at the facts of the matter, three things are obvious.
First, the Peters projection terribly distorts those parts of the world it supposedly promotes.
Second, there is a perfectly good alternative to the Peters that is an equal area map and depicts shape of tropical Third World regions with considerable accuracy — the Goode’s projection.
Third, there is nothing new about The New Cartography. The Peters projection is a knock-off of a projection that was developed by James Gall in 1885 and quickly disappeared from the radar screen of serious cartography, probably because it lies so badly.