iNtroductioN

mEntAl mAPsCARtogRAPhiC mAPswhAt mAkEs mAPs PoPulAR?FunCtions oF mAPsReference mapsThematic mapsNavigation mapsPersuasive mapsmAP usEsElECtEd REAdings

introduction

It should be easier to read a map than to read this book. After all, we know that a picture is worth a thousand words. Everyone from poets to politicians works from the assumption that nothing could be easier to understand and follow than a map. The very term “map” is ingrained into our thinking. We use it to suggest clarification, as in “Map out your plan” or “Do I have to draw you a map?” How ironic, then, to write a book using language that is, supposedly, more complicated than the thing we’re trying to explain!

The problem is that maps aren’t nearly as simple and straightforward as they seem. Using a map to represent our detailed and complexly interrelated surroundings can be quite deceptive. This isn’t to say that maps themselves are unclear. But it’s the environment, not the map, that you want to understand. A map lets you view the environment as if it were less complicated. There are advantages to such a simplified picture, but there’s also the danger that you’ll end up with an unrealistic view of your sur-roundings. People who manage critical natural and human resources all too often make decisions based on maps that inherently are oversimplified views of the environment.

In this book, we’ll define a map as a spatial representation of the environment that is presented graphically. By representation, we mean something that stands for the environment, portrays it, and is both a likeness and a simplified model of the environment. This definition encompasses such diverse maps as those on walls, those that appear ephemerally on a computer screen and then are gone, and those held solely in the mind’s eye, known as cognitive or mental maps. You may envision the environ-ment by using cartographic maps, which are what most people think of as traditional maps drawn on paper or nowadays displayed on computer screens. Or you can use mental maps, which often are made light of by many people although they are really the ultimate maps that you use to make decisions about the environment. Let’s look more closely at mental and cartographic maps.

xvi intRoduCtion

MeNtaL MaPs

As a child, your mental map was probably based on direct experience, connected pathways such as the routes from your home to school or playground. You had a self-cen-tered view of the world in which you related everything to your own position. The cartoon in figure I.1 graphi-cally portrays this type of mental map. As an adult, you can appreciate this cartoon because you see how ineffi-cient the child’s mental map is. But the truth is that you will often resort to this way of visualizing the environ-ment when thrown into unfamiliar surroundings. If you go for a walk in a strange city, you will remember how to get back to your hotel by visualizing a pathway like that in the cartoon. Landmarks will be strung like beads along the mental path. Even if you might be able to guess at a more direct route back, you may feel more comfort-able following the string of landmarks to assure that you do not get lost.

Most of your mental maps are more detailed than this, however. For one thing, you take advantage of indi-rect as well as direct experience. You acquire informa-tion through TV, photographs, books and magazines, the Internet, and other secondary sources. You can transcend your physical surroundings and visualize dis-tant environments, even those on the other side of the planet at different historical periods. Your mental maps become incredibly complex as they expand to encom-pass places and times you have never seen and may never be able to visit.

As you grow older, your self-centered view of the world is replaced by a geocentric view. Rather than relating everything to your own location, you learn to mentally orient yourself with respect to the external environment. Once you learn to separate yourself from your environ-ment, you don’t have to structure your mental map in terms of connected pathways. You can visualize how to get from one place to another “as the crow flies”—the way you would go if you weren’t restricted to roads and other connected routes. It’s your adult ability to visualize the “big picture” that makes the cartoon amusing.

Sharing your mental map with others, either in conversation or on maps that you draw, is much easier when you use a geometrical reference framework, or a framework on which you can easily describe and deter-mine locations, distances, directions, and other geo-graphic relationships. The system of cardinal directions (north, south, east, and west) is such a framework. You can pinpoint the location of something by stating its cardinal direction and distance from a starting location. You can say, for example, that the store is two miles north of a particular road intersection or the police station is 200 meters west of the courthouse.

This visualization of space is based on Euclidian geometry, the geometry you learned in elementary and high school. It’s the geometry that says that parallel lines never cross, that the shortest distance is a straight line, that space is three-dimensional, and so on. The ability to visualize the environment in terms of Euclidian geometry is an essential part of developing a geocentric mental map.

Figure i.1 the geometry

of a child’s mental

map is based on direct

experience and connected

pathways.

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CARtogRAPhiC mAPs xvii

But even if you develop mental maps based on Euclidian geometry, they will only be correct over small areas. That’s because the earth is spherical, and the spherical geometry of the earth’s surface is inherently non-Euclidian. (We’ll see in chapter 1, for example, that north–south lines on the earth, called meridians, aren’t parallel but, rather, converge to a common point at the poles.) Very few of us have well-developed spherical mental maps.

Even if you’re able to visualize the world geocentrically in terms of Euclidian or spherical geometry, it’s hard for most people to transform their mental map to a carto-graphic map in a geometrically accurate manner. Try drawing, from memory, a map of the area in which you live. The hand drawn map will tell you a great deal about the geometrical accuracy of your mental map. Not only will you probably draw the places you know best with the greatest detail and spatial accuracy, you’ll probably draw things important to your life and leave off those that you don’t care about.

Few people’s mental maps correspond with cartographic maps. Figure I.2 shows the distorted visual image that a person from Michigan’s Upper Peninsula might have of the country. Tongue in cheek as this map may be, it captures the fact that people visualize their own region as far more important than the rest of the world. In the same way, your mental maps emphasize your own neighborhood, with distant places less well visualized.

It’s important to recognize these biases in your mental maps. The quality of your mental maps is crucial, because

your behavior in the environment largely depends on them. You relate to your surroundings as you visualize them, not necessarily as they really are. If the discrepancy between your mental maps and the real world is great, you may act in self-defeating or even disastrous ways. Luckily, you don’t have to rely solely on mental maps, since carto-graphic maps have been created for a multitude of places and features in the environment.

cartograPhic MaPs

A cartographic map is a graphic representation of the environment. By graphic, we mean that a cartographic map is something that you can see or touch. Carto-graphic databases or digital image files are not in them-selves maps, but are essential to current methods for the creation of maps. In a similar vein, an exposed piece of photographic film or paper doesn’t become a photograph until it has been developed into a slide or paper print.

Cartographic maps come in many forms. Globes, physical landscape models, and Braille maps for the blind are truly three-dimensional objects, but most maps are two-dimensional line drawings or images of the earth taken from aircraft or orbiting satellites that have been cartographically enhanced. Cartographic maps have been carved, painted, or drawn on a variety of media for thousands of years, and printed maps have been produced

Figure i.2 the united

states as seen through

the eyes of a resident

of michigan’s upper

Peninsula.

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xviii intRoduCtion

for the last five centuries. Today you are just as likely to see maps displayed electronically on a computer monitor or other screen device.

What gives a graphic representation of the environ-ment its “mapness?” Many mapmakers say that carto-graphic maps have certain characteristics, the five most important being the following:1. Maps are vertical or oblique views of the environment,

not profile views like a photograph of a side of your home taken from the street.

2. Maps are created at a reduced scale, meaning that there has been a systematic reduction from ground distance to map distance, as we will see in chapter 2.

3. Except for globes and landscape models faithfully representing the earth’s curvature, maps are made on a map projection surface. A map projection is a math-ematically defined transformation of locations on the spherical earth to a flat map surface, as we explain in chapter 3.

4. Maps are generalized representations of the environment. Mapmakers select a very limited number of features from the environment to display on the map, then display these features in a simplified manner. Insignificant features won’t be shown, the sinuosity of linear features and area boundaries will be reduced, and several small ground features may be aggregated into a single feature on the map, as explained in chapter 10.

5. Maps are symbolized representations of the envi-ronment. The generalized features are then shown graphically with different map symbols. The map-maker will use different point symbols, line widths, gray tones, colors, and patterns to symbolize the features, as we describe further in chapters 7 and 8. Names, labels, and numbers that annotate the map are also important map symbols.

Figure i.3 different types of maps lie along a “mapness” continuum. their position on the continuum is defined by how many

characteristics of maps they possess. in the examples above, all are vertical views.

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whAt mAkEs mAPs PoPulAR? xix

A cartographic map need not have all five characteris-tics of maps, but it should have at least one. You can think of different types of maps as being at different places on a “mapness” continuum defined by the degree to which they exhibit these four characteristics. This continuum is illustrated in figure I.3 for a gradation of map types depicting part of Crater Lake National Park in Oregon.

The topographic map, which shows elevations or landforms as well as a limited set of other features, in the left quarter of the illustration strongly reflects all five characteristics and is a good example of what most people think of as a map. The orthophotomap in the center of the illustration also has all five characteristics, since topographic map symbols have been printed over a geometrically corrected aerial photo called an orthopho-tograph (orthophoto for short). An orthophoto is cor-rected to a constant scale on a map projection surface, and hence has four of the five characteristics. Finally, the aerial photograph from which the orthophoto was made is not on a map projection surface and varies in scale with elevation differences on the ground. The aerial photo only has the characteristic of being a graphically represented vertical view of the environment, but is still a form of cartographic map. All the other maps are also vertical views.

As you can see from this illustration, there are multitudes of cartographic maps, each somewhere along the “mapness” continuum. The variety is so great that from now on we’ll shorten the term “cartographic map” to simply “map,” in accord with what you’re used to hear-ing these products called.

what Makes MaPs PoPuLar?

In scrutinizing the nature of maps, the obvious ques-tion is, “What accounts for their widespread popularity?” There are four main factors:1. Maps are convenient to use. They are usually small and

flat for ease of storage and handling. Thus, they bring reality into less unwieldy proportion for study.

2. Maps simplify our surroundings. Without them, our world often seems a chaos of unrelated phenomena that we need to organize in order to understand our environment. The selection of information found on a map, on the other hand, is clear at a glance. The world becomes intelligible.

3. Maps are credible. They claim to show how things really are. The coordination between symbol and real-ity seems so straightforward that we’re comfortable

letting maps “stand for” the environment. When we manipulate maps, we expect the results to apply in our surroundings. Maps, even more than the printed word, impress people as authentic. We tend to accept the information on maps without question.

4. Maps have strong visual impact. Maps create a direct, dramatic, and lasting impression of the environment. Their graphic form appeals to our visual sense. It’s axiomatic that “seeing is believing” and “a picture is worth a thousand words.”

These factors combine to make a map appealing and useful. Yet these same four factors, when viewed from a different perspective, can be seen as limitations.

Take convenience. It’s what makes fast food popular. When we buy processed foods, we trade quality for easy preparation. Few would argue that the result tastes like the real thing made from fresh ingredients. The same is true of maps. We gain ease of handling and storage by creating a prepared image of the environment. This rep-resentation of reality is bound to make maps imperfect in many ways.

Simplicity, too, can be seen as a liability as well as an asset. Simplification of the environment through mapping appeals to our limited information processing ability, while at the same time it reduces the complexity and—potentially—the intricacies we need to understand. By using maps, you can reduce the overwhelming and confusing natural state of reality. But the environment remains unchanged. It’s just your view of it that lacks detail and complexity.

You should also question the credibility of maps. The mapmaker’s invisible (to you) hand isn’t always reliable or rational. Some map features are distortions; others are errors; still others have been omitted through oversight or design. So many perversions of reality are inherent in mapping that the result is best viewed as an intricate, controlled representation. Maps are like statistics— people can use them to show whatever they want. And once a map is made, it may last hundreds of years, although the world keeps changing. For all these reasons, a map’s credibility is open to debate.

Also be careful not to confuse maps’ visual impact with proof or explanation. Just because a map leaves a powerful visual impression doesn’t make it meaningful or insightful. A map is a snapshot of the portion of the environment at a point in time. From this single view, it is sometimes difficult or impossible to understand the processes that caused the patterns we can see on maps. For explanations you must look beyond maps and confront the real world.

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FuNctioNs oF MaPs

Maps function as media for the communication of geographic information, and it is instructive to draw par-allels between maps and other communication media. You can first think of maps as a reference library of geo-graphic information. Maps serving this function, called reference maps, are more efficient geographic references of the locations of different features rather than maps with a certain theme. Reference maps let you instantly see the position of features and estimate directions and distances between them. Explaining these spatial rela-tionships among features in writing would take hundreds of pages.

Maps can also function like an essay on a particular topic. Like a well-written theme, a map can focus on a specific subject and be organized so that the subject stands out above the geographical setting. We call maps that function as geographic essays thematic maps.

Maps are tools for navigation, equal in utility to a compass or GPS receiver. When you get into your car and drive across your city, you are navigating the land. When you find your route on a subway or bus system, you are navigating a transit system. In the first case, you will use a road map, and in the second case you will use a transit map.

When you step into an airplane and fly to a distant city, you must do air navigation (assuming you are the pilot). And when you motor or sail between two destinations on a body of water, you are marine navigating. In these two cases, you will use navigation charts to plan your route in advance and to guide you on your trip.

Maps are also instruments of persuasion. Like a written advertisement or television endorsement, some maps are made to persuade you to buy a particular product, to make a certain business decision, or to take a targeted political action. These maps often are more sales hype or propaganda than a graphic representation of the environment, and you should view such maps with suspicion.

Let’s take a closer look at maps with each of these different functions.

Reference mapsThe earliest known maps, dating back several thousand years, are of the reference type. On reference maps, sym-bols are used to locate and identify prominent landmarks and other pertinent features. An attempt is made to be as detailed and spatially truthful as possible so that the information on the map can be used with confidence. These maps have a basic “Here is found…” characteris-tic and are useful for looking up the location of specific geographic features. On reference maps, no particular

Figure i.4 Reference map

examples include (A) a world

globe, (B) the northwest section

of a united states road and

recreation atlas map, (C) the terra

grande united states wall map,

and (d) a section of the oregon

state highway map.

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FunCtions oF mAPs xxi

feature is emphasized over the others. As much as pos-sible, all features are given equal visual prominence.

The topographic map and remote sensor images (orthophotomap, orthophotograph, and aerial photo-graph) in figure I.3 are excellent examples of reference maps, because they show a variety of phenomena with about the same emphasis given to each. Reference maps are often produced in national mapping series, such as

the U.S. Geological Survey (USGS) topographic map series. The topographic map segment in figure I.3 is from such a series.

Topographic maps show and label natural features, including mountains, valleys, plains, lakes, rivers, and vegetation. They also show cultural features, such as roads, boundaries, transmission lines, and buildings. One thing that distinguishes topographic maps from

Figure i.5 thematic maps for oregon show (A) annual precipitation as colored regions of a continuous surface, (B) vegetation

provinces as uniform areas, (C) rural and urban population by dots and graduated circles, and (d) population density as uniform

colors within counties.

Coastal Coniferous Forest

Pacific LowlandMixed Forest

Cascade Coniferous ForestMixed Forest - Alpine Meadow

Sierran Mixed Forest -Alpine Forest

Blue Mountains Coniferous Forest -Alpine Meadow

Intermountain Semi-desert

Oregon Vegetation Provinces

20,000 - 30,00010,000 - 19,9995,000 - 9,9992,500 - 4,9991,500 - 2,499500 - 1,499

30,00060,000120,000

240,000480,000

Oregon Population - 2000-

Each colored dot represents 500 people living eitherin the vicinity of towns with less than 500 people,or in rural residences in the general vicinityof the dot.

INCORPORATED CITIES AND TOWNS

0.8 - 9.910.0 - 19.920.0 - 49.950.0 - 99.9

100.0 - 200.0

6001,500

Persons per Square Mile

Oregon Population Density-2000-

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xxii intRoduCtion

other map types is the use of contour lines to portray the shape and elevation of the land.

The geographic reference information on topographic maps and remote sensor images makes them useful to professional and recreational map users alike. They are used in engineering, energy exploration, natural resource conservation, environmental management, public works design, commercial and residential planning, and outdoor activities like hiking, camping, and fishing.

Globes and atlases are reference maps that show natural and cultural features in more generalized form than topographic maps. School wall maps are another form of reference map, as are the road maps and recreation guides produced for each state (figure I.4).

Thematic mapsUnlike reference maps, which show many types of features but emphasize no particular one over the others, thematic maps show a single type of feature that is the theme of the map. While reference maps focus on the location of different features, thematic maps stress the geographical distribution of the theme. A climate map (figure I.5A) showing how average annual precipitation changes continuously across the state of Oregon is a good example. A map showing the areal extent of Oregon vegetation provinces (figure I.5B) likewise shows the geographic distribution of physical features.

Many thematic maps show the geographic distribution of concepts that don’t physically exist on the earth. One example is a map showing Oregon’s rural population with dots and urban population with varia-tions in circle sizes (figure I.5C). Another example is the Oregon population density map in figure I.5D. Although you can’t actually see population density in the physical environment, maps showing the spatial distribution of such statistical themes are very useful to experts in demo-graphics and other fields.

Thematic maps ask, “What if we wanted to look at the spatial distribution of some aspect of the world in this particular way?” Figure I.5D, for example, asks, “What if we wanted to look at population density by taking the 2000 population census totals for Oregon counties as truth, dividing each total by the area of the county to get a population density, generalizing the densities into seven defined categories, and representing each density category with a special symbol?”

Take another look at each map in figure I.5 and note how each theme is superimposed on a background of county outlines. Most thematic maps have similar back-ground information to give a geographical context to the theme. Be careful not to use the geographical reference

information to find specific locations or to make precise measurements. Remember, that’s not the intent of the-matic maps; it’s what reference maps are for. When using thematic maps, focus on their function of showing the geographic distribution of the theme.

Navigation mapsAs you’ll see in chapter 13, several types of maps are specially designed to assist you in land, water, and air navigation. Many of these maps are called charts—maps created specifically to help the navigator plan voyages and follow the planned travel route.

Figure i.6 (A) topographic maps, (B) nautical charts, and (C)

aeronautical charts are important tools of land, water, and

air navigation, respectively.

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FunCtions oF mAPs xxiii

A topographic map, such as the segment in figure I.6A, not only is a valuable reference map, but it also is one of the most important land navigation tools. Hikers, off-road vehicle enthusiasts, and land management profes-sionals use topographic maps to find their way across the land. The topographic map shows ground features such as roads, trails, lakes, and streams that are both landmarks and obstacles. Contour lines on the maps are equally important, as they allow you to determine elevation changes and estimate the slopes you’ll encounter along a route. This information will help you estimate the time and physical effort it will take to complete your trip. In addition, topographic maps are drawn on map projec-tions that allow you to measure distances and directions

between locations along your route (in chapters 11 and 12, you’ll learn how to make these measurements).

Nautical charts, such as the southeastern corner of the San Juan Islands, Washington, chart in figure I.6B, are maps created specifically for water navigation. Recre-ational and commercial boat navigators use the detailed shoreline, navigational hazard, and water depth informa-tion on the chart to plan the “tracks” that they will follow between ports or anchorages. As you’ll see in chapter 13, each chart is made on a special map projection that allows you to quickly and easily measure the distance and direc-tion of each track. Another type of nautical chart found in a Current Atlas (see chapter 13 for an example) gives you information about the currents you must deal with

Figure i.7 disproportionately large or small map symbols may create the impression that the west Bank was more or less

crowded with israeli military checkpoints than it actually was at the time when the information for the map was collected (2002).

xxiv intRoduCtion

on a particular day and hour. This information is of criti-cal importance in planning your time of departure and estimating the time of arrival at your destination.

Aeronautical charts are maps designed for the air navigator. Figure I.6C is part of an aeronautical chart covering the state of Washington. Air navigation involves planning and following safe routes between air-fields, and the chart is filled with information important to safe flying. Notice the detailed information shown on the chart for the Tri-cities airport. In chapter 13, you’ll learn what these map symbols mean, and you will see how pilots use the information on the chart to find dis-tances, directions, and travel times between destinations. Air navigation also involves maintaining a safe altitude above the ground, and you’ll see that aeronautical charts show the heights of towers and other obstructions to navigation, as well as contours and special ground eleva-tion symbols that help navigators quickly determine the minimum safe in-flight altitude.

Persuasive mapsMaps have always played a role in decision making, and mapmakers can deliberately try to persuade you to choose a particular product or support a certain position. Some of these persuasive maps distort or misrepresent to such an extent that they become propaganda maps. Such propaganda is common, especially on advertising, political, and religious maps. Since all maps distort real-ity, what could be easier than to make this distortion serve a special company, organization, or point of view? Unless we know enough to question every map, how would we suspect anything was wrong? Let’s look at sev-eral examples of persuasive maps that either are or border on propaganda.

One type of propaganda involves disproportionate symbols as a means of persuasion. Mapmakers must

make symbols overly large in relation to the size of the feature on the ground; otherwise, the symbols wouldn’t show up at reduced map scales. In propaganda mapping, mapmakers carry this normal aspect of cartographic symbolization to extremes.

Take two maps of Israeli military checkpoints in the West Bank that we made from information gathered in 2002 (figure I.7) Notice on the map on the right the large soldier symbol for each checkpoint. By using such large symbols, we have made the West Bank appear crowded with military checkpoints. The map on the left has the same number and placement of soldier symbols one-quarter the size of those on the right map. Now the West Bank appears far less crowded with checkpoints. This is an interesting example because the two maps of the same information have opposite propagandizing effects of increasing or decreasing the sense of safety for Israelis, or of intimidating Palestinians to a lesser or greater degree.

Presenting a misleading number of features on a map is another tool of persuasion that grades into propaganda. Nineteenth century railroad maps such as figure I.8 are classic examples. Notice that the map scale has been selectively enlarged along the artificially straight main line from Duluth, Minnesota, to Sault Ste. Marie, Michigan. The map shows several dozen stops along the main and feeder lines, some of which are towns. By mapping every stop, the railroad company is trying to persuade investors, settlers, and riders to choose it over a competing railroad. The following commentary from the Inland Printer shows how far this practice of planned map distortion went:

“This won’t do,” said the General Passenger Agent, in annoyed tones, to the mapmaker. “I want Chicago moved down here half an inch, so as to come on our direct route to New York. Then take Buffalo and put it a little farther from the lake.

Figure i.8 on this portion of the

nineteenth century duluth, south shore

& Atlantic railroad map, the area along

lake superior was deliberately enlarged

to show all stops along the line.

FunCtions oF mAPs xxv

“You’ve got Detroit and New York on different latitudes, and the impression that that is correct won’t help our road.

“And, man, take those two lines that compete with us and make em twice as crooked as that. Why, you’ve got one of em almost straight.

“Yank Boston over a little to the west and put New York a little to the west, so as to show passengers that our Buffalo division is the shortest route to Boston.

“When you’ve done all these things I’ve said, you may print 10,000 copies—but say, how long have you been in the rail-road business, anyway?”

(New York Herald, "Some Railway Map-Making," Inland Printer, vol. 15, 1895, p. 500)

Map simplification can also be used for persuasion purposes. Figure I.9 shows two maps of illegal West Bank settlements in the mid-1980s. Both maps come from the same weekly news magazine. One map depicts 16 settlements, while the other shows 30 settlements. Which is correct? The truth, revealed deep in the maga-zine’s text, is that there were 45 illegal Israeli settlements in the West Bank region when these maps were made. The legend, at the least, should have provided this infor-mation. The makers of these maps, whether intention-ally or not, presented a picture that favored the Israeli cause. You should never overlook the possibility for such political bias in mapping.

It pays to be especially cautious of novel or artful advertising maps, because they are invariably more eye-catching than factual. Consider figure I.10, made to promote Bend, Oregon, as the center of Oregon in terms of travel distance. Distance rings in 50-mile increments centered on Bend have been drawn on the map to show the travel distance to other locales. The idea of drawing equally spaced distance rings outward from Bend is absurd, since travel to the city is by road, not air. The

16 West BankSettlements

30 West BankSettlements

West

Bank

A B

Figure i.9 the need for map simplification can easily be

used to create a map that borders on propaganda. here

west Bank settlements on maps of two scales are shown.

Figure i.10 on this deceptive map,

distances from Bend, oregon, are shown

by concentric distance circles spaced 50

miles apart. the travel distances the map

shows are “as the crow flies,” not by road.

xxvi intRoduCtion

shortest road distance from Bend to Corvallis, for example, is 130 miles, not the 100 miles shown by the distance rings.

Whether you realize it or not, mapmakers are constantly molding your attitudes. Of course, they aren’t the only people guilty of persuasion and propaganda. But the effect of map propaganda is especially insidious because so many people believe that maps are neutral and unbiased. The consequences are often dramatic: A year’s vacation is ruined or a retirement nest egg is spent on a land parcel in a swamp.

MaP use

Map use is the process of obtaining useful informa-tion from one or more maps to help you understand the environment and improve your mental map. Map use consists of three main activities: reading, analysis, and interpretation.

In map reading, you determine what the mapmak-ers have depicted and how they’ve gone about it. If you carefully read the maps in figure I.11, for instance, you can describe the maps as showing mortality from all types of cancer for white males and females from 1980 to 1990 within data collection units called Health Service Areas. Reading the main map legends, you learn that the mortality rate is the number of deaths per one hundred

Figure i.11 white male

and female 1980–1990

cancer mortality rates

in the united states by

health service Area.

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mAP usE xxvii

thousand people, and that mortality rates have been generalized into seven categories shown by a two-color sequence with lighter to darker tones for each color. Light to dark blue and brown represent low to high mortality on both maps, but the range for each category differs on the two maps. You need to discover this to understand that males have higher overall deaths from cancer. There is no explanation of how the category limits were selected, but the maps appear to have about the same number of Health Service Areas in each category. Finally, the smaller legends tell you that areas with sparse mortality data are shown with a diagonal line pattern, and you can see a few patterned areas on both maps.

Part I of this book examines these and many other facets of map reading. You will become familiar with map scale, map projections and coordinate systems, land partitioning methods, different ways of portraying land-forms, maps that show qualitative and quantitative infor-mation, and ways of expressing map accuracy.

Learning to read the information on maps is only the first step. Your curiosity or a work assignment may lead you to go further and analyze the information on one or more maps. Part II of this book is devoted to map analy-sis. In this stage of map use, you make measurements and look for spatial patterns. We have seen that topographic maps and navigational charts are tools for the measure-ment of distances, directions, and surface areas.

Analysis of the spatial patterns on the maps in figure I.11 is particularly thought-provoking. While it’s comforting to believe that cancer is unpredictable, analysis of these maps shows that’s not true. If you focus on the patterns on these maps, you find that cancer mortality rates are far from random across the country. Regional clustering of high and low rates occurs for both males and females. You see a cluster of high mortality in Kentucky and western West Virginia (the brown coun-ties to the right of the center) and low mortality in Utah and southeastern Idaho (the blue-green counties toward the upper left), for example. It’s unlikely that this high and low clustering of deaths occurred by chance.

If you next focus on the spatial correspondence of mortality rates on the two maps, you find that eastern Kentucky and western West Virginia appear to have the highest cancer mortality for both men and women. The upper Midwest and Northeast, along with Northern California (the brown counties along the western coast), have the next highest overall male and female mortality. Some areas have high mortality rates for one sex but not

for the other. For instance, the Mississippi Delta region along the south-central coast has high mortality rates for males but not for females.

You may see clusters of high and low mortality on the two maps, but someone else may not see things the same way. Quantitative measures of spatial patterns on a map and spatial association among patterns on two or more maps add rigor and repeatability to your map analysis, and we have devoted two chapters (chapters 17 and 18) to these important aspects of map analysis.

After analyzing the maps in figure I.11 and finding spatial patterns of high and low cancer mortality, your curiosity may now be aroused still further. You may wonder how to explain the patterns and the spatial cor-respondences between the two maps. Finding such expla-nations takes you into the realm of map interpretation. To understand why things are related spatially, you have to search beyond the map. To do so, you may draw on your personal knowledge, fieldwork, written documents, interviews with experts, or other maps and images.

In your search, you’ll find that cancer deaths are associated with many factors, including industrialized working environments, mining activities, chemical plants, urban areas, ethnic backgrounds, genetics, and personal habits of eating, drinking, and smoking. You’ll find that people die from cancer because of contaminants in their air, water, food, clothing, and building materials. Some local concentrations of high or low cancer mortal-ity, however, don’t seem to fit this pattern, suggesting that there must be other causes or that people have migrated in or out of the area. In this book, we will focus on the first two of the map use processes—reading and analysis.

Since maps reflect a variety of aspects of environ- mental knowledge, map use is intertwined with many disciplines. It is impossible to appreciate them in isola-tion. The more different fields you study, the better you will be at using maps. Map interpretation grows natu-rally out of an appreciation of a variety of subjects. The reverse is also true. An appreciation of maps leads to a better understanding of the world around you; for the subject of maps, after all, is the world itself.

This brings us to a final, important point. As you gain an understanding of map use, be careful not to confuse the mapped world with the real world. Remember, the reason you’re using maps is to understand the physical and human environment. The ultimate aim of map use is to stimulate you to interact with your environment and to experience more while you do.

xxviii intRoduCtion

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