General notes on “necessary” map elements
(Almost) every map we produce or encounter will have some combination of elements usually deemed “necessary” or “required.” The typical list can be both useful and problematic.
On one hand, the checklist helps remind us of what might be unfinished work—our own or in evaluating others’. On the other hand, treating the list as a checklist might lead to sloppiness or the application of inappropriate conventions.
That said, what follows is some brief guidance.
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The default mapping settings of your GIS software are not designed for your map or its purpose, argument, and audience. To rely on these default settings is, indeed, to default—to fail to fulfill an obligation.
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If you are not a designer and/or you are new to map design, please know that this is not easy. It takes time.
Think of it this way: most of us are not professional writers but what we write must be legible and effective; most of us are not seasoned orators, but we have to make our points clear and accessible when we speak and present our work. Mapping and other forms of graphic communication are no different: if our audiences don’t understand our work, it’s on us—not them—to fix it. And, just like written and spoken communication: you get better with practice.
Descriptive Title
There’s no overstating it: aside from the map image itself, the title is the first and greatest opportunity to set the tone of the map. A “descriptive” title, for our purposes, should include the what, where, and when of the map’s information.
Legend with pertinent information, including units
The legend should translate the information you have chosen to map. But be careful: Legends can obfuscate as much as they can clarify. Aim for transparency, legibility, and succinct thoroughness. The legend is your chance to anticipate your reader’s questions.
Sufficient Context
Combined with the scale bar and north arrow (or equivalent), your map needs to provide enough context for your intended audience to orient themselves within the frame of the map. This context can be provided with additional basemap layers, text labels, a reference locator map, or other devices that help to clarify locations relative to one another within the image. Again, thoughtful consideration of your audience is key. Different readers will have varying levels of familiarity with the area or region in question.
Scale Bar (or equivalent)
Be mindful of the size, position, and units of your scale bar.
Maps that cannot be resized (i.e., those designed for printing) could include scale text instead if this is intuitive for the map’s intended audience. For example, this is common in site plan/maps whose readers are architects. Maps that change scale across the image could include an alternative approach, such as a scaled graticule, drawn to reflect distortions in scale.
North Arrow (or equivalent)
North need not be “up” (and is often not, for example, when mapping Manhattan). We don’t assume the orientation of a map. Thus we need to communicate its orientation.
Like a scale bar, be mindful of the size and position of the north arrow. Alternatives to an arrow or compass include, for example, a graticule.
Relevant Data Sources
Which data sources require direct referencing on the image will vary from project to project. For example, maps that are compiled within a larger report may only feature a reference for the thematic layer, while other data sources are within the report’s bibliography. Use your judgment, and remember the reasons why we cite. If those purposes are fulfilled, you’re good.
Generally speaking, most of our maps can use an abbreviated Author-Date reference style, assuming the nature of the data included in our mapping are evident by the labeling, text, annotation, and legend description offered on the map. For more, see Citing Maps & Data.