an informative legend that shows the meaning of map symbolsCONCISE AND WELL-PLACED WORDS COMMUNICATE information clearly. Mapmakers design titles, legends, and notes to help map readers understand and remember their maps. Scale bars, grids, and north arrows are also basic elements in the layout of maps. The care with which you compose and finish the elements that surround and support a map make it work.
Building better maps through wording and placement requires revisiting map layout techniques from chapter 1. It means providing information without disrupting the visual hierarchy that emphasizes the main map content. It also means paying attention to nuances and details of order, placement, and relationships in content. Excellent map design is definitely detailed work, but the more you know about the design tools that you have in GIS and the cartographic conventions for marginal elements, the quicker you will be able to complete professional, readable map designs.
Designing better maps means completing a map with the following:
an informative legend that shows the meaning of map symbols
hierarchies in text content, descriptions of mapped calculations, and logical line breaks and spacing
well-designed marginal elements, including indicators of scale and direction
Legends present information that allows the reader to interpret the map and understand its symbols. In this section, you will learn the basic legend components for a variety of standard thematic mapping methods. Legends also assist in interpreting base information, so you will see examples of reference map legends in this chapter. However, many basemap themes are easily understood within the map context when they are well designed. Use your cartographic license to omit the more obvious supporting data types from the map legend, such as terrain shading and features labeled on the map (for example, airports, towns, roads, and rivers).
Map legends explain map symbols. The basic types of thematic maps have fairly conventional legend content. GIS software provides only some of this content within legend tools. This section provides an overview of what you should be aiming for as you adjust default legends for the following types of thematic maps:
choropleth
qualitative area fills
dot (density)
isolines
proportioned symbols
segmented symbols
Choropleth—A legend for a choropleth map states the data range for each color or pattern used (figure 3.1). Choropleth maps of one variable are produced using graduated colors as area fills that may be organized as sequential or diverging schemes.
Figure 3.1 A choropleth map legend. Figure by A. Dennis, Department of Geography, The Pennsylvania State University (Penn State Geography).
As you label a choropleth map legend, you need to decide whether to do the following:
round numbers for breaks or within labels
increment labels (for example, 0–10 and 10–20 or 0–9 and 10–19; this issue is linked to rounding)
use the word “to” or a dash within ranges (this may depend on whether the data includes negative numbers)
label breaks between classes with single numbers rather than labeling class ranges
order classes with the highest numbers at the top (like the vertical axis on a graph) or at the bottom of the legend
label ranges with the actual values represented by the symbol, creating gaps between ranges
use the true maximum and minimum in the dataset to label ranges, or use statements such as “fewer than 100 people” or “more than 150 percent” for extreme ranges
add annotations that elaborate on the meaning of ranges, or meaning of class breaks, to assist map reading
Qualitative area fills—Maps that use qualitative area fills provide a descriptive label for each legend color or pattern (figure 3.2). Creating logical groupings of related categories assists map reading.
For area symbols, the legend boxes should present colors or patterns in the same way they appear on the map. If map polygons have outlines, use the same outline color and weight in the legend. If there are no lines between colors on the map, consider presenting the symbols that way in the legend (figure 3.2). If colors are seen immediately adjacent to each other on the map, show them that way in the legend as well (figure 3.1).
Figure 3.2 A qualitative area map legend. Figure by P. Limpisathian, Penn State Geography.
Dot (density)—At their simplest, dot map legends define the amount that one dot represents (figure 3.3). Dot map symbols are intended to show density (the dots are not counted, and they do not show precise location). A dot map is improved if you include example densities in a set of legend boxes in addition to defining the dot value (figure 3.4). You may need to manually construct the density boxes for the legend.
Figure 3.3 The minimum legend for a dot map defines the meaning of a single dot.
Figure 3.4 A complete legend for a dot map includes example densities. Figure by A. Dennis and P. Limpisathian, Penn State Geography.
Isolines—The simplest legend on a contour map or other isoline map is a statement of the isoline interval. If the isolines are augmented through use of index lines, hachures for closed depressions, or supplemental lines, you may choose to identify the meaning of these different line symbols in the legend. If color fills are used between isolines to enhance the map pattern, present those colors in a legend. You may label the colors with data ranges or label the isolines that mark breaks between colors. Example isoline legends are shown in figures 3.5 and 3.6.
Figure 3.5 The minimum legend for an isoline map defines the isoline interval.
Figure 3.6 Classified hypsometric tints labeled at breaks, akin to labeling contours where colors change. Figure by P. Limpisathian, Penn State Geography.
Figure 3.7 Legends on proportional point symbol maps show the largest and smallest symbols and a range of sizes between these extremes to aid interpolation. Figure by P. Limpisathian, Penn State Geography.
Figure 3.8 Legends for graduated symbol maps are much like choropleth map legends (graduated color maps). They define the data range for each symbol size. Figure by P. Limpisathian, Penn State Geography.
Figure 3.9 Legends for multivariate symbols, such as segmented bar symbols, walk the reader through the meaning of each symbol component. This legend explains bar heights and bar segment colors in two steps. Data source: Pennsylvania Department of Environmental Protection. Figure by A. Dennis and P. Limpisathian, Penn State Geography.
Proportioned symbols—Proportioned point symbol legends present a set of example symbol sizes to demonstrate the amounts that map symbols represent. The best strategy is to show the smallest and largest symbol sizes seen on the map, so the map reader can interpolate between these extremes. Include one or more intermediate size symbols to assist map reading (figure 3.7).
You may use symbols rounded to even amounts that approximate the data range rather than exact minimum and maximum symbol sizes in the point symbol legend. If the largest symbol on the map is too large to be repeated in the legend, consider labeling the amount next to that symbol (and a few other very large symbols) on the map and use a more manageably sized large symbol in the legend.
If you use graduated rather than proportional point symbols, be sure to clarify that sizes do not represent precise data values. List data ranges for each symbol in the legend (figure 3.8). Follow choropleth legend conventions for graduated symbol maps.
Segmented symbols—Segmented symbols, such as pie charts and bar graphs, require custom legend design. Construct a generic looking symbol and label each segment. If the segmented symbols also vary in size, create a two-part legend that uses a different set of example symbols to define sizes (figure 3.9).
Basemap themes may be easy enough to understand that they need not be included in the legend, especially because they are not the main topic of the map but support overlaid information. Figure 3.10 shows a legend for a variety of basemap layers grouped into one legend with subheadings to organize related classes. This additional structure also separates basemap themes from the data legend for content overlaid on the basemap.
Transportation and boundaries are shown in figure 3.10 as lines on a white background. Consider the backgrounds for these features as they appear on the map. You may want to include a gray fill for the legend or around the lines so their color can be matched to the lines on the map, especially if the roads are white. Similarly, administrative areas may also have specific fill colors, so the legend would then show boxes with both the boundary line and the fill if that helps to interpret the map.
A raster land-cover layer in the background uses some color associations that will be obvious, such as blue for water and green for forest. But a reader may need help with the connection between reds or another hue you choose for a developed land sequence. A legend is likely needed if you include a full variety of other land-cover types, such as wetland, grassland, shrubland, scrubland, and barren areas. The colors in the figure 3.10 legend are grouped but retain the default colors provided with US National Land Cover Data (NLCD).
There are many other map symbols that you may find useful to include in legends. You should customize legend titles and headings, labels, and layout to best describe the meaning of these symbols. Do not feel, though, that every symbol must be in a legend.
When you customize a legend beyond the basic settings that can be made for legend properties, you will sever the link between the data and the legend. The legend then becomes a graphic that does not change in response to symbol changes on the map. There are four basic strategies for customizing legends in GIS:
1. Insert a legend, convert it to graphics, ungroup the graphics, and edit individual elements.
2. Add drawn elements and additional text to an inserted legend.
3. Convert map symbols to graphics and copy and paste examples from the map to build a legend.
4. Construct the entire legend manually with text and drawing tools.
With any of these strategies, you will need to manually update legend elements if you change the map. For example, if you change symbol colors and sizes, you will need to manually make corresponding changes in the legend graphics. If you change the data ranges represented by map colors or other symbols, you will need to manually edit the text information in the legend. To minimize the manual work required to ensure a match between map and legend symbols, legend customization should be done at the very end of the map design process.
The example in figure 3.11 shows how many elements a legend breaks into when you convert it to graphics and ungroup the elements. Each block of color, each line symbol, and each label becomes an editable element. You can move these elements, change color and line characteristics, and edit the text to better suit the map.
Figure 3.10 Compound legend for the example basemap elements from chapter 2. Transportation, boundaries, and land cover each have subheadings within the legend. Figure by P. Limpisathian, Penn State Geography.
Figure 3.11 Example choropleth map legend (left) converted to graphics (right).
Figure 3.12 Added text, to the left of the legend colors, explains class breaks. Two median breaks are noted, and black lines across these two breaks are added drawings. Figure by A. Dennis, Penn State Geography.
Figure 3.13 The three selected symbols were copied and pasted into the legend area being built in the upper right of the frame. The map shows the relative proportion of family (pink) and nonfamily (red) households by census tract in part of Salt Lake City.
Figure 3.14 A manually constructed legend for a two-variable map shown in chapter 8. Figure by A. Dennis, Penn State Geography.
Annotations added to a map legend (figure 3.12) clarify the meaning of groups of map classes and of particular breaks between colors. The underlying legend remains live; it will update if classes or colors are changed. The annotations, however, will need to be manually edited because they are not linked to the map data.
Another handy way to construct a custom legend is to convert map features to graphics and then copy and paste example symbols to compile a legend. This is especially useful for multivariate chart symbols that are difficult to redraw.
The example in figure 3.13 shows pie charts converted to graphics. Three example symbols are copied into a legend area to begin preparing a detailed explanation of symbols. Remember, converting either the legend or map symbols to graphics will break the link to the data, so do this only when you are at the very end of the map design process.
The two-variable legend in figure 3.14 was manually constructed with ArcGIS drawing tools. Lines and boxes were drawn, colors set, and text placed to build this customized legend.
The ArcGIS legend tools get you part of the way to a custom legend. You will sometimes want to copy, augment, or draw parts of your legend to explain customized map symbols.
When you begin creating a map using GIS, the wording of basic text elements is set at defaults. The legend may be labeled “Legend” and raw layer names will display as headings. Symbols will be labeled with attributes from data tables. These text elements are fine as cues to what is mapped when you are first exploring the spatial distributions of your data. But when you get serious about map design, you will want to edit text elements.
Your goal is to communicate the map content clearly using a hierarchy of detail. You also want to refine labels so spacing within and between lines of text conveys clear associations with other map elements. This section asks you to bring a critical eye to the content and arrangement of your map title, subtitles, legend titles, and notes—elaborating on the discussion of layout in chapter 1.
In addition to the labels within the map body, you can add a variety of marginal text elements to a map. The map usually has a title and legend title. You may also add subtitles and notes to explain the data that is mapped or the purpose of the map to your reader.
Marginal text on maps should be succinct with minimal punctuation. An example of hierarchy in map text follows:
1. Short title:
Population Distribution, 2010
2. Legend title elaborates:
Number of people by county
3. Note completes detail:
The area of each square symbol is proportioned to the number of people in a county. The legend presents example symbol sizes from the many symbols shown on the map.
The title (1) is a straightforward statement of the overall map topic. More detailed information about the map content is stated in the legend title (2), and further explanation is offered in the note (3). The legend and note are also shown in figure 3.15. Sentences and full punctuation are used only in the smallest text element: the note.
Figure 3.15 has fairly straightforward content. But how do you handle wording for more complex concepts that can be mapped? It might seem straightforward to require that a map title list who, what, where, and when, and that both the numerator and denominator of a mapped ratio be made clear. In reality, these details can produce an impenetrable title.
Figure 3.15 Map segment showing a hierarchy of text wording. The map title (not shown) is “Population Distribution, 2010.” Data sources: US Census Bureau, made with Natural Earth. Map updated by P. Limpisathian, Penn State Geography.
Figure 3.16 Example map layout. Segments of this map are shown enlarged in the figures that follow. Source: US Census Bureau. Made with Natural Earth. Map updated by P. Limpisathian, Penn State Geography.
Here is an accurate but poor title for the map shown in figure 3.16:
A map showing the distribution of the percent of people indicating one or more races including American Indian and Alaska Native who are under age 18 in 2010 by county in the United States prepared using Census 2010 Redistricting Data
The potentially unwieldy list of who, what (numerator and denominator), where, and when can be parceled out among the title, subtitles, legend, and notes to help map readers understand the map.
For individual maps, where and when can often be listed in a subtitle, one step down from the title in the hierarchy of text on the map. When you are preparing a series of maps, where and when are often covered in the introductory material for the group of maps. They need not be repeated in the title of each map. All of the US map examples shown in this chapter are 2010 updates of maps in an atlas of population data published by the US Census Bureau. In the examples, “United States” is not included in map titles (figure 3.16) because the whole series is clearly about the United States.
What and who for a map can range from obvious to convoluted. The details of numerators and denominators of ratios may be difficult to understand. They can be explained more fully in the legend title that augments a summary map title. Who can also be complex if, for example, a subset of a group or multiple groups in a population are being described.
Details, like source information, should not appear in a title and should be reported in a note in small text that is not prominent on the map. Other content suited to notes in small text includes publisher, author credit, projection information, explanation of map calculations, and tips for map reading.
The following is the shortened title used for the example atlas map in figure 3.16:
Percent Under Age 18, 2010
One or More Races Including American Indian and Alaska Native
The legend title in figure 3.17 (enlarged from figure 3.16) picks up many of the details from the inappropriately long title proposed at the beginning of this example. The annotations on the left side of the legend further assist the reader in understanding the map.
Figure 3.17 The legend title and legend annotations from an example map of Census 2010 population data. Data sources: US Census Bureau, made with Natural Earth. Map updated by P. Limpisathian, Penn State Geography.
Notes from various places on the map are pulled together in figure 3.18 to show the level of content that belongs in the smallest text on the map. These details should not be in the map title or legend title. The title should be straightforward enough to invite the reader to be interested in your map. Offer them details in the fine print rather than distracting them from your map content with too many words.
The previous titles for the US Census Bureau atlas map are somewhat wordy but meet needs for clarity. Race groups are presented in two ways in the atlas on which these maps are based (including and excluding people who indicated more than one race on their census form). Simpler titling would suit the same content presented in a different context. The following alternative set of title, legend, and note wordings is less specific in race group naming and allocates more of the detail to notes (figure 3.19):
1. Alternative title:
Native American Children, 2010
Figure 3.18 Additional notes from the “Percent Under Age 18” map (moved together to show them in one figure).
Figure 3.19 An alternative wording for the map of Census 2010 data shown in previous figures. The map title, legend title, legend annotations, and note have been collected into a corner of the page. This wording may not conform to language approved within the agency for describing race groups.
Data source: US Census Bureau. Made with Natural Earth. Maps updated by P. Limpisathian, Penn State Geography.
2. Legend title:
Percent of Native American population who are under age 18 by county
3. Explanatory note:
The Native American population mapped includes both American Indian and Alaska Native (AIAN) groups. This population includes people indicating their race as AIAN alone and those indicating AIAN in combination with other races.
Describing a calculation in few words can be harder than you expect. You might end up suggesting a different map topic than you intend if you do not pay close attention to the wording.
The map shown in figure 3.20 is related to the American Indian and Alaska Native map discussed in the previous section.
Figure 3.20 Legend wording used for the map showing the distribution of young Hispanic population. Source: US Census Bureau. Made with Natural Earth. Map updated by P. Limpisathian, Penn State Geography.
This example seems to be simpler for wording the legend title because Census 2010 ethnicity data is categorized into only two groups: Hispanic and Not Hispanic (ethnicity is a different categorization than race). The wording used in the atlas map is shown in figure 3.20 and graphed in figure 3.21.
Figure 3.21 The map shown in figure 3.20 presents the ratio of the yellow segment to the sum of the green and yellow segments of the population in this bar graph.
The legend caption chosen for the atlas map is fairly wordy. You might wonder why. Can the number of words be cut in half and still get the idea across? Some wording options follow with notes to alert you to potential misinterpretations.
1. Correct but wordy:
Percent of people indicating Hispanic or Latino origin who are under age 18 by county
2. Ambiguous:
Percent Hispanic under 18 by county
Instead of the intended meaning (graph on left in figure 3.22), option 2 could suggest percent of total population (right in 3.22) or percent of total under-18 population (middle in 3.22).
3. Confusing:
Under 18 Hispanic percent by county
Option 3 might mean percent of the total under-18 population who are Hispanic (middle graph in figure 3.22).
4. Shorter but OK:
Percent Hispanic who are under 18 by county
Caption 4 should be interpreted accurately (left graph in figure 3.22).
Simple graphs (figures 3.21 and 3.22) demonstrate the nuances of potential meaning expressed by the four previous legend captions. You do not want to confuse your map reader with the text you provide, and you also do not want them to misinterpret your text because it is excessively brief.
Figure 3.22 The ambiguous caption “Percent Hispanic under age 18” could steer a map reader to different interpretations, shown here with explanatory graphics (figure 3.21 defines the colors used).
Be sure that your map text says what you mean to say. As you work on a map, ask others to describe the map to you to check that you have not gone off-track in your wording. Do not describe the map to them; have them describe it to you.
If you are having difficulty balancing brevity and accuracy for title and legend wording, consider adding a note that explains the calculation. You may include the formula for the calculation in a note. Figure 3.23 contains a portion of the note for a diversity map, which is an example of this strategy. Readers interested in the math behind a mapped distribution will gain more from the map if they are sure of what it presents. Readers who are less interested in the math can ignore the details because they are listed in a small note.
Figure 3.23 A note that describes the diversity calculation and national context for an Esri map service using US Census Bureau data. Map source: USA Diversity Index map service by Esri. Data source: US Census Bureau. Figure by P. Limpisathian, Penn State Geography.
After you have decided on your map wording, you need to attend to the nuances of line breaks and spacing between text elements. Breaks and spaces take over some of the roles of sentence structure and punctuation that are not fully used for map text. You learned about the importance of proximity for map interpretation in chapter 1. This issue is addressed in greater detail here.
A legend from an example you have seen before is shown in figure 3.24, but it has been revised with thoughtless breaks and spacing. Do you know what this title means? Something about “transportation and land,” “using Prince George’s County,” and “Maryland land use,” perhaps? Which symbols do “Institutional” and “Green Area” label?
The revised example in figure 3.25 shows the same content with better breaks, a hierarchy of type sizes, and more spacing between elements. In the title, the two words in “Land Use” are now on the same line. “Maryland” has been pulled into the subtitle. The legend titles are separated from the subtitle, so you can tell they are clearly part of the legend. Additionally, a larger gap between the two columns of the legend clarifies that the land-use labels apply to the area symbols on the left.
Note that the legend in figure 3.25 is not titled “Legend.” It is better practice to use legend titles and headings that describe legend content. After all, it is quite obviously a “Legend,” so that label is superfluous.
Figure 3.24 Text for a map of Prince George’s county, Maryland, with poor line breaks and compressed spacing between elements.
Figure 3.25 Spacing and line breaks are used to clarify map content for the Prince George’s County map.
Figures updated by P. Limpisathian, Penn State Geography.
The legend area of a Census 2010 map is shown in figure 3.26 without spacing between text elements or a hierarchy of sizes and styles. The annotations on the left are particularly difficult to interpret.
The corresponding legend in the atlas (figure 3.27) uses spacing and type hierarchies to separate text elements and to clarify which parts of the legend they refer to. The legend title is larger than the other text, asking the reader to attend to its content before the details below it.
The annotations to the left of the legend are each separated by spaces and are closer to the portion of the legend to which they refer than to anything else. The white legend box is moved down so that the “Hispanics are young” phrase does not seem to refer to it. The legend is an improvement on the one in figure 3.26.
Figure 3.26 Legend text without careful spacing or hierarchy for the Census 2010 map showing the distribution of the young Hispanic population.
Data sources: US Census Bureau, made with Natural Earth. Maps updated by P. Limpisathian, Penn State Geography.
You should break lines to retain the logic of phrases within the text. You do not need to use the entire length of the available space before breaking to the next line.
You should use spaces carefully as well. Keep lines in a text block closer to each other than to other text elements on the map. Likewise, put a text element closer to the element it labels than to anything else on the map. This is much the same logic you learn for placing labels within the body of the map in chapter 7. You want to consider positioning for marginal text elements as carefully as you do for map labels.
Figure 3.27 Legend text spacing and hierarchies used in the well-designed map of Census 2010 data.
Scale bars and direction indicators can be customized to fit into your map’s visual hierarchy and give it a distinctive look. Be aggressive, but not excessive, in editing the appearance of these marginal elements.
Map scale is communicated three ways: as a graphic bar scale, a verbal scale, and a representative fraction (absolute scale). An example of each scale type is shown in figure 3.28. The graphic bar scale remains most accurate in the dynamic environments in which we look at maps because it resizes as map size varies with zooming, screen resolution, and reproduction.
Detailed scale bars are useful for maps that will be used for distance measurement. Only a general indication of distances is usually needed on thematic maps that present statistical data, so a simple scale bar is more suitable.
Figure 3.28 Three forms of map scale: (from the top) graphic scale, verbal scale, and representative fraction.
Figures updated by P. Limpisathian, Penn State Geography
A set of scale bars with increasing visual prominence is shown in figure 3.29. The first three scale bars are better suited to thematic maps, and the next two are better suited to reference maps. The simple scale bars encourage approximate distance estimates (for example, 10 or 20 km), and they do not distract attention from the map message. The detailed scale bars have sufficient length and segmentation that they let the user calibrate distances and make measurements across the map. A scale bar that is dark, wide, and detailed with many segments (such as the bottom scale bar) is too dominant for a simple thematic map that will not be used for detailed distance measurements. However, the same scale bar may be appropriate for a detailed reference map where its prominence supports a primary use of the map—measuring distances with relative precision between points on the map.
Figure 3.29 Example scale bar designs.
A good scale bar presents rounded units that the map reader can easily use. Figure 3.30 shows a scale bar with poorly chosen units and one with more useful rounded units of 5 and 10 miles. Pay attention to the ticks set along the scale bar too. It is not helpful to produce a scale bar representing 10 kilometers that has three subdivisions. Does your reader want to know the length that represents 3.33 and 6.67 kilometers?
Figure 3.30 Always use round-number units for scale bars as shown in the bottom example. Figure updated by P. Limpisathian, Penn State Geography
Be aware that on small-scale maps, such as a map of the world, scale varies across the map. A single scale bar will not be an accurate representation of scale for much of the map. With web Mercator cached mapping at multiple scale levels, a competent web service shows changes in scale bar lengths as scales become dramatically larger as latitude increases (discussed in chapter 1). The nominal scale for generating a projection, which you set in your GIS interface, does not necessarily give you the scale for a particular portion of that map.
Scale bars can also be converted to graphics and edited, though they will no longer update if the map scale is changed. An example custom scale bar combines metric and English units to accommodate an international audience (figure 3.31). Make these types of edits only after the map extent and scale has been finalized.
Figure 3.31 This elegant scale bar from a National Park Service (NPS) map shows mile and kilometer lengths back to back. Source: NPS.
GIS software offers a wide variety of north arrow designs. Once you select a north arrow style, there are few ways to customize it. You can set the north arrow size and adjust its background. If you want to do further customization, you will need to draw an arrow from scratch. That small design effort can give you a distinctive element of your map, acting much like a logo for your work. But a north arrow is rarely the most important feature on a map, so keep that in mind when designing this element. Do not let it get so large or elaborate that it draws attention away from the map content (figure 3.32).
On small-scale maps, north may be in many directions. When lines of longitude converge within a map projection, a north arrow will always be wrong for some parts of the map (figure 3.33).
Do not use a north arrow when the direction of north varies across the map. For example, maps of the United States or Canada created using customary conic projections should not include a north arrow because longitude lines converge toward the pole. It is also fine to omit the north arrow from maps of a place familiar to the intended audience.
Figure 3.32 Example north arrow designs available in ArcGIS that range from simple to ornate. Source: ArcGIS. Figure updated by P. Limpisathian, Penn State Geography.
When north is multiple directions, replace the north arrow with the graticule to indicate direction. The graticule is a grid of lines of longitude and latitude and thus makes a fine directional indicator. As with north-arrow design, the graticule is supporting information, so it should be a subdued design element that does not compete with map content.
Many graphic elements and effects can be used to enhance the primary components of a map layout:
drop shadows
line styles for frames
background patterns or gradients
full compass roses
scale bars
extent indicators
colorful logos
decorative display fonts
geometric shapes
Figure 3.33 Do not put a north arrow on a map like this because north is many different directions within the map. Data source: Made with Natural Earth. Map updated by P. Limpisathian, Pennsylvania State University Geography.
An example map of Waterton-Glacier International Peace Park includes many decorative elements (figure 3.34). They compete for the reader’s attention and distract from the main message of the map—vegetation types. They also look fairly silly, are hard to read, and visually clash with each other. The scale bar is far longer than it needs to be, and it contains more detail than necessary. The title is set in a complicated cursive font with a drop shadow that reduces text legibility. The compass rose is too large and attempts a place of prominence with the busy design.
Figure 3.34 Excessively decorated elements of a map of Waterton-Glacier International Peace Park in Alberta and Montana.
The same map has been redesigned in figure 3.35. The important map content stands out, and supporting information is pushed into the background where it belongs.
Figure 3.35 An improved visual hierarchy for the Peace Park map elements.
Data sources: US Geological Survey (USGS), National Geospatial-Intelligence Agency/National Aeronautics and Space Administration (NGA/NASA), NPS, Canada Centre for Mapping and Earth Observation. Maps by E. Guidero, Penn State Geography.
Any decorative element can be an effective addition to a map, but only if it is used purposefully. For example, a drop shadow may either attract too much attention away from the map itself, or it may effectively elevate a small, yet important, element to the foreground. Extent indicators that sweep across the page to connect an enlarged area to its location on a smaller-scale map may be vital for one map’s purpose, but they may confusingly obscure other data on a map with a different goal. A simple tiny label, such as “Enlarged area,” next to the location on the smaller-scale map may be a better solution if the extent indicators will be too prominent in the map’s visual hierarchy.
The enlargement of the northeastern portion of a population density map is boldly portrayed in figure 3.36. The map is redesigned in figure 3.37 with a more subdued cue to the enlargement. Small text explains the relationship between the two areas. The white box and darker blue water link the inset map to its extent, outlined on the main map. Scale bars are included to further emphasize the difference in scale between the two mapped areas.
A background may seem like the one element that should always be lowest in the visual hierarchy—a background in the true sense of the name. But consider a television sportscast—whirling, flashing, colorful, and detailed designs form the background for the information on screen. Should we conclude that colorful and busy backgrounds are the modern way to design information displays? Well, think about how much information is on that display—perhaps four final scores or three performance statistics. Broadcast designers use all that background activity to keep you looking at a screen that has a small amount of information on it. You should be confident that your map contains enough information to attract your reader. Color and detail should be used to make your mapped information stand out, rather than its background. Do not let your background become too high in the visual hierarchy of your map; it is definitely not the most important element of the layout.
Figure 3.36 Overly bold lines to the inset map showing population in the northeastern United States.
Figure 3.37 This map uses subtler indicators of the inset map location and extent.
Data sources: US Census Bureau; made with Natural Earth. Maps updated by P. Limpisathian, Penn State Geography.
