ArcGIS Blog

Cartographic design: Inset maps

By Aileen Buckley, Mapping Center Lead

Recently we were asked if there are any cartographic standards for inset maps. Here are a few guidelines:

Purpose

First, consider why the inset map is needed. Inset maps are sometimes used to show related themes of data at smaller scales, for example:

Cartographic Inset Maps - Figure 1

Most often inset maps are used to provide either an overview of the area or a close up of a section or sections of a map. Here are some examples:

Cartographic Inset Maps - Figure 2
Cartographic Inset Maps - Figure 3
Cartographic Inset Maps - Figure 4
Cartographic Inset Maps - Figure 5

When designing inset maps to provide an overview, consider the map readers and determine what locational information they need in order to properly establish the location of your study area in their minds. For inset maps that are close ups, you can provide further detail for the areas that are rather congested on the main map.

Form

Inset maps will either be open or closed forms. A closed form inset uses an immediately recognizable outline (a state, a country, the world, etc.) An open form is a portion of any of these that is a little harder for the reader to locate without additional information, unless your audience is already familiar with how you have cropped the area shown in the inset.

If you are using a closed form, familiarity will allow you to get away with providing less basic locational information for the audience. If you are using an open form, you may need to give the audience more clues about the area mapped. Base data generally includes some or all of the following:

Design

There are a few standards that you can follow. In general, the same design considerations that you apply to the main map should be applied to the inset map(s). Here are some tips:

Carefully consider whether to add inset maps to your page layout.  Inset maps can help readers view an area from multiple vantage points – use them when this would be helpful to your map readers.  Avoid using inset maps to simply fill up white space; doing this can actually detract from your map’s message and provide more confusion than clarity.

When you design an inset map, you will need to consider the same cartographic decisions that you do for your main map since the same cartographic standards apply to these maps as well.

Additional Resources

You can find additional information about these and other map elements in:

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